Len Blackwell

Massey University · Institute of Fundamental Sciences

Practical domestic monitoring of the menstrual cycle requires measurements of urinary metabolites of reproductive hormones: oestrone glucuronide (E1G) and pregnanediol glucuronide (PdG). Data reported in the literature are expressed as (i) concentration, without or with either creatinine- or specific gravity correction, or (ii) excretion rates. Thi...

Oestrone glucuronide (E1G) is monitored during the menstrual cycle because it reflects the follicular production of oestradiol (E2), the rate of which increases as the follicles grow. Despite several recent assertions to the contrary, the urinary E1G concentration is an inadequate indicator of E2 because it is confounded by variations in the rate o...

It has been suggested that it is possible to monitor the menstrual cycle by measuring the concentration of urinary reproductive steroids. This neglects the variation in void volume and in urine production rate. In neither case has any systematic analysis been reported previously. Overnight urine samples were collected each day for one complete cycl...

The use of urinary analytes to monitor physiological processes relies on making the correct measurement. Three alternatives are commonly contemplated: concentration, creatinine-corrected concentration and excretion rate. Of these, the latter is the most reliable, but is perceived by some to be difficult to measure. This has led to the more frequent...

Ovulation monitors are widely used by women wishing to achieve pregnancy. However, there are few data substantiating claims that these devices enhance the probability of becoming pregnant. In one report it is concluded from the cumulative pregnancy rate that the use of the Clearblue Easy Fertility Monitor increased the pregnancy rate. In a second r...

Identifying the return of fertility with cervical mucus observations is challenging during the postpartum period. Use of urinary measurements of estrogen and progesterone can assist in understanding the return to fertility during this period. The purposes of this study were to describe the postpartum return of fertility by an analysis of total estr...

The patterns of a woman's normal ovarian activity can take many forms from childhood to menopause. These patterns lie on a continuum ranging from no ovarian activity to a fully fertile ovulatory cycle, but among the other defined patterns are cycles with anovulatory ovarian activity, including luteinized unruptured follicles (LUFs), and ovulatory c...

Natural family planning (NFP) methods have served many generations well, and in particular, the symptothermal or symptohormonal methods. The comparison of daily mucus and temperature records for individual cycles with daily hormone measurements, which is now possible, shows that some of the assumptions underlying NFP may not be completely accurate....

Many women choose to monitor their menstrual cycle and a variety of physiologically relevant measurements are employed. The demand is so great that many apps and devices are now available and online monitoring is imminent. However, many of the current apps are unreliable for at least two reasons. First, it is often the case that the data collected...

An enzyme linked immunosorbent assay (ELISA) for measurement of pregnanediol-3α-glucuronide (PdG) excretion rates in urine samples diluted to 150 mL/h before analysis is described. The sensitivity of the 9 optimized standard curves was 0.093±0.070 μmol PdG/24 h, with the multiple combined standard curves having a mean mid-point (EC50) of 6.88 μmol...

Excel’s “line chart” has several peculiarities that can yield misleading representations of data. However, in Excel 2010 it is possible to combine “line charts” with “scatter charts” which exacerbates the capacity to be misleading.

STUDY QUESTION Do the basal body temperature (BBT) shift and the cervical mucus markers for the beginning of the post-ovulatory infertile phase (POIP) of a menstrual cycle agree with the corresponding urinary pregnanediol glucuronide (PdG) threshold value?

Ligand-binding assays, such as immunoassays, are usually analysed using standard curves based on the four-parameter and five-parameter logistic models. An estimate of the uncertainty of an analyte concentration obtained from such curves is needed for confidence intervals or precision profiles. Using a numerical simulation approach, it is shown that...

F-specific filamentous phage of Escherichia coli (Ff: f1, M13, or fd) are long thin filaments (860 nm × 6 nm). They have been a major workhorse in display technologies and bionanotechnology; however, some applications are limited by the high length-to-diameter ratio of Ff. Furthermore, use of functionalized Ff outside of laboratory containment is i...

Abstract Human milk lysozyme was conjugated with estrone glucuronide to give a monoacylated conjugate, two disubstituted isoforms and one trisubstituted isoform in 99.4% yield. The conjugates were pure and highly inhibited (>98%) by the anti-estrone glucuronide antibody. The clearing curves were biphasic for all four conjugates but a three minute i...

Objective To compare the results of a computer programme based on the Trigg's tracking system (TTS) identification of the basal body temperature (BBT) shift day from daily records of BBT values (TTS transition day), with the BBT shift day identified from the same records using the Sensiplan(®) symptothermal method of natural family planning. Method...

What are the characteristics of, and how variable are, individual normal menstrual cycle profiles of excretion rates for the urinary metabolites oestrone glucuronide (E1G) and pregnanediol glucuronide (PdG)? There is a continuum of menstrual cycle profiles that differ from standard textbook profiles but which can be understood simply in terms of gr...

In this study, fluorescent proteins (FPs) were engineered to self-assemble into protein particles inside recombinant Escherichia coli while mediating the display of various protein functionalities such as maltose binding protein or IgG binding domains of Protein A or G, respectively. Escherichia coli produced functional FP particles of up to 30% of...

Fertility awareness constitutes fundamental knowledge for every woman and is an important tool for health professionals. The objective of this review is to show how fertility awareness can be useful in the assessment of a woman's health. The main techniques for detecting ovulation are explained, and then the events that characterize a normal menstr...

I. Introducción. La fertilidad es un estado biológico transitorio que depende del potencial de fertilidad de la pareja (Vigil et al., 2006). Durante el ciclo de vida de la mujer, el ovario pasa por distintos estados en relación a su capacidad ovulatoria y de secreción hormonal. El concepto de ciclo ovárico como un continuo-conocido este como el «co...

The UNDP/WHO/World Bank/Special Programme of Research, Development and Research Training in Human Reproduction (Geneva) set up a study to determine whether it is feasible for women to monitor their ovarian activity reliably by home testing. Daily self-monitoring of urinary hormone metabolites for menstrual cycle assessment was evaluated by comparis...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A rapid quantitative immunoassay for estriol-16-glucuronide by Surface Plasmon Resonance (SPR) sensing has been developed and applied to urine samples from non-pregnant and pregnant subjects. The assay was based on a partially-purified polyclonal antibody (pAb) raised in sheep, which showed negligible cross-reactivity with estrone-3-glucuronide and...

IntroductionHydrogen ExchangeSulphonium YlidesIsotope Effects in Elimination ReactionsSubstitution ReactionsReferences

For the quantitative evaluation of low levels of an estriol metabolite of estriol (estriol-16-glucuronide (E3-16G)) in liquid media, we developed a simple and highly sensitive immunoassay using a surface plasmon resonance (SPR) biosensor which did not require any time-consuming sample pretreatment steps. E3-16G was conjugated to ovalbumin (OVA) thr...

Sheep liver cytoplasmic aldehyde dehydrogenase was purified to homogeneity to give a sample with a specific activity of 380 nmol NADH min ⁻¹ mg ⁻¹ . An amino acid analysis of the enzyme gave results similar to those reported for aldehyde dehydrogenases from other sources. The isoelectric point was at pH 5.25 and the enzyme contained no significant...

A direct enzyme linked immunosorbent assay (ELISA) system has been optimized as a reference method for the measurement of first statistically significant rises in estrone glucuronide excretion rates in human urine by analysing samples pre-diluted at the time of the collection by the women subjects to a constant urine production rate of 150 mL/h. Va...

Lysozymes (3.2.1.17) from goose (Anser anser) egg white, turkey (Melagris gallopavo) egg white, phage T4 and human milk were compared with hen egg white lysozyme in their ability to clear a suspension of Micrococcus lysodeikticus. All of the lysozymes, except hen egg white lysozyme, catalysed the clearing of the Micrococcus lysodeikticus suspension...

A TEMPO/hypochlorite/bromide oxidant has been used for the conversion of aryl and steroidal glucosides to the corresponding glucuronide conjugates in good (48-74%) yield. An isoflavone glucoside failed to undergo this transformation.

A TEMPO/hypochlorite/bromide oxidant has been used for the conversion of aryl and steroidal glucosides to the corresponding glucuronide conjugates in good (48-74%) yield. An isoflavone glucoside failed to undergo this transformation.

A study was conducted to determine the accuracy and reliability of the Home Ovarian Monitor for measuring estrone glucuronide (E1G) and pregnanediol glucuronide (PdG) during ovulatory cycles as a means of monitoring ovarian activity. Approximately 60 ovulating women in three centres collected timed specimens of urine (3h or more) for a total of six...

The defined estrone glucuronide-lysozyme conjugate E3, that is acylated solely at K33, was used as a probe for the steric requirements of the active site cleft of chicken type lysozymes. When the immune complex was formed with an anti-estrone glucuronide antiserum, the rate of lysis of the E3 conjugate with the large bacterial substrate Micrococcus...

Three structurally characterized estrone glucuronide-lysozyme conjugates, E1 (a 60:40 mixture acylated at K3 and K97), E3 (acylated at K33), and E5 (acylated at both K33 and K97) were isolated and purified using a combination of cation-exchange chromatography on S-sepaharose in 7M urea and hydrophobic interaction chromatography on butyl sepharose....

The preparation of conjugates destined for use in homogeneous enzyme immunoassays requires careful control to maximize the yield of conjugate, limit the level of substitution and obtain highly inhibitable conjugates. Furthermore, previous studies have shown that the acylation position and orientation of haptens in enzyme conjugates is important in...

Estrone glucuronide conjugates of hen egg white lysozyme were prepared by the mixed anhydride and active ester coupling procedures. Both methods gave good yields of conjugates, but the active ester procedure gave a more diverse range of products, making it less suitable for preparing conjugates for homogeneous enzyme immunoassay. Conjugation of lys...

Acid-polyacrylamide gel electrophoresis (acid-PAGE) was used for analysis of lysozyme-estrone glucuronide conjugates. The resolution of the system allowed the identification of individual conjugate families which differed only in the position of acylation or in the number of estrone glucuronide units. Acid-PAGE was a good alternative to denaturing...

Application of time series analysis to a database containing serial pregnanediol data from 113 complete ovulatory menstrual cycles contributed by 83 women of proven fertility and 68 cycles for which pregnanediol values were available over the ovulatory period, detected the first statistically significant risk in pregnanediol excretion for all cycle...

Despite the existence of several protocols, problems appear to persist in the small scale chemical synthesis of radiolabeled 11-ketotestosterone from cortisol. We investigated the possibilities of using the mild oxidant pyridinium dichromate for the oxidative cleavage of the dihydroxyacetone side chain of cortisol and 17 beta-hydroxysteroid dehydro...

The crystal structure of 2-O-[17-oxoestra-1,3,5(10)-trien-3-yl]-beta-D-glucopyranosiduronic acid hydrate, C24H30O8.-H2O, is reported. The angle between the mean plane of the A ring of the steroid and the mean plane of the glucuronide is 14.1 (5)degrees.

The crystal structure of methyl 1-O-[3,16 alpha-dihydroxy-estra-1,3,5(10)-trien-17 beta-yl]-2,3,4-tri-O-acetyl-beta-D-glucopyranosiduronate, 1, clearly shows the beta-linkage of the carbohydrate moiety with estriol and unambiguously shows the trans relationship of the 17 alpha- and 16 beta-protons. C-13 NMR studies on 1 and on other estriol 16 alph...

The crystal structure of methyl-1-O-[3,16α-dihydroxy-estra-1,3,5(10)-trien-17β-yl]-2,3,4-tri-O-acetyl-β-Dglucopyranosiduronate, 1, clearly shows the β-linkage of the carbohydrate moiety with estriol and unambiguously shows the traps relationship of the 17α- and 16β-protons. 13C NMR studies on 1 and on other estriol 16α- and 17β-glucuronide derivati...

Although the oxidation of aldehydes by aldehyde dehydrogenase is usually considered to be irreversible, Hart & Dickinson (1978) have shown that anhydrides of carboxylic acids could be reduced to aldehydes by enzyme.NADH mixtures. In a later study Motion et al (1988) demonstrated that acylation of aldehyde dehydrogenase.NADH complexes by acetic anhy...

Estrone glucuronide conjugates of hen egg white lysozyme were prepared by both the mixed-anhydride and active-ester coupling procedures. Both methods gave good yields of conjugate but the active-ester procedure gave a more diverse range of products consistent with a greater acylating ability. Unreacted lysozyme which was present in all cases was re...

The cytosolic (Class 1) aldehyde dehydrogenase (AlDH) from sheep liver has been crystallized in a form suitable for X-ray diffraction studies. The crystals, grown by vapour diffusion using 6.5 to 7.5% methoxypolyethylene glycol 5000 as precipitant, at pH 6.5, are orthorhombic with cell dimensions a = 80.7, b = 92.5, c = 151.6 A, space-group P2(1)2(...

p-Chloromercuribenzoate (PCMB) at stoichiometric levels reacts with a thiol group of the binary NAD+ complex of sheep liver cytoplasmic aldehyde dehydrogenase (E.NAD+) faster than with the corresponding thiol group of either the free enzyme or the binary enzyme. NADH complexes. High concentrations of propionaldehyde have a protective effect against...

An efficient and convenient procedure for the synthesis of estriol 16- and 17-monoglucuronides from estriol is described. This is achieved by the selective protection and deprotection of the hydroxy groups in estriol, Koenigs-Knorr reactions with methyl 1-bromo-1-deoxy-2,3,4-tri-O-acetyl-alpha-D-glucopyranuronate and subsequent hydrolysis. The prod...

The kinetics of the cytosolic aldehyde dehydrogenase (ALDH) catalysed oxidation of propionaldehyde are complex. For example, at concentrations of propionaldehyde below about 200 μM propionaldehyde (low propionaldehyde concentration) the Lineweaver-Burk plot is linear, but at higher propionaldehyde concentration (20 mM) substrate activation occurs (...

The release of NADH from the enzyme.NADH complexes was rate limiting at 37 degrees, for the oxidation of propionaldehyde by sheep liver cytosolic aldehyde dehydrogenase. Marked substrate activation was observed at this temperature as was activation by p-(chloromercuri)benzoate. Activation of enzymic activity may be of importance in vivo.

Time-series analysis was applied to the urinary total estrogen data from 142 ovulatory menstrual cycles to determine the first statistically significant increase as a marker for the beginning of the potentially fertile phase. Application of the Trigg's tracking signal to each cycle detected an increase in urinary total estrogens above the baseline...

The nature of the dietary component responsible for adipocytes having the ability to respond to Glucose Tolerance Factor (GTF) was investigated. Rats were raised on either a control diet or one of three diets differing only in the protein source (torula yeast, brewer's yeast, or casein). Only in adipocytes from rats fed the torula yeast diet did a...

The kcat value for the oxidation of propionaldehyde by sheep liver cytosolic aldehyde dehydrogenase increased 3-fold, from 0.16 s-1 at pH 7.6 to 0.49 s-1 at pH 5.2, in parallel with the increase in the rate of displacement of NADH from binary enzyme.NADH complexes. A burst in nucleotide fluorescence was observed at all pH values consistent with the...

Pyrophosphate ions activate the steady-state rate of oxidation of propionaldehyde by sheep liver cytosolic aldehyde dehydrogenase at alkaline pH values. The steps in the mechanism governing the release of NADH from terminal enzyme. NADH complexes have been shown to be rate-limiting at pH 7.6 [MacGibbon, Buckley & Blackwell (1977) Biochem J. 165, 45...

Although studies on the effect of pH on aldehyde dehydrogenase have been carried out in a number of laboratories, the results of these studies do not give a complete picture of the mechanism of the aldehyde dehydrogenase catalyzed oxidation of propionaldehyde over an extended pH range. The enzyme catalyzed oxidation reaction at pH 7.0 and 7.6 is ge...

An in-vitro culture system was developed in which primary mouse follicles from 12-16-day-old mice grew to the preovulatory stage. The important determinants of growth in culture were the inclusion of stroma with the primary follicles, the age of the mouse, the presence of FSH and LH, the use of culture dishes with a hydrophobic membrane and the use...

A nucleophilic group in the active site of aldehyde dehydrogenase, which covalently binds the aldehyde moiety during the enzyme-catalyzed oxidation of aldehydes to acids, was acylated with the chromophoric aldehyde trans-4-(N,N-dimethylamino)cinnamaldehyde (DACA). Acyl-enzyme trapped by precipitation with perchloric acid was digested with trypsin,...

1. Cationic fractions were isolated from a low chromium (less than 0.2 ppm) commercial yeast extract in an attempt to purify the material responsible for glucose tolerance factor (GTF) activity observed in a standard yeast assay system. 2. Following previously described procedures a fraction with GTF activity but containing negligible chromium was...

Acylation of the aldehyde dehydrogenase.NADH complex by acetic anhydride leads to the production of acetaldehyde and NAD+. By monitoring changes in nucleotide fluorescence, the rate constant for acylation of the active site of the *enzyme.NADH complex was found to be 11 +/- 3 s-1. The rate of acylation by acetic anhydride at the group that binds al...

It is now well accepted that a woman can conceive from an act of intercourse for a maximum of only about 7 days of her menstrual cycle. The reliability of natural family planning depends on identifying this window of fertility without ambiguity. Several symptomatic markers, cervical mucus and basal body temperature, have been used extensively and w...

The displacement of NADH from the aldehyde dehydrogenase X NADH complex by NAD+ was followed at pH 7.0, and the data were fitted by a non-linear least-squares iterative procedure. At pH 7.0 the decay constants for the dissociation of NADH from aldehyde dehydrogenase X NADH complexes (1.62 +/- 0.09 s-1 and 0.25 +/- 0.004 s-1) were similar to the val...

Despite the fact that it is an aldehyde, glyoxylic acid is not a substrate for sheep liver cytoplasmic aldehyde dehydrogenase; instead it functions as an inhibitor of both the esterase and dehydrogenase activities. From a consideration of the inhibition patterns it is concluded that glyoxylic acid does not bind in the catalytic propionaldehyde-bind...

Die Mischung aus Chrom, Nicotinsäure und den Ami- - nosäuren Glycin, Glutaminsäure und Cystein, die die Geschwindigkeit der CO2-Produktion in lebenden Hefe-Kulturen anregt, wurde einem Trennschema unterworfen, das auf einer Ionenaustausch-Chromatographie beruht, die bereits zur Trennung der Cr-haltigen Fraktionen von Brauereihefe verwendet wurde.

The mixture of chromium, nicotinic acid and the amino acids glycine, glutamic acid and cysteine which stimulates the rate of CO2 production in a yeast bioassay system was subjected to the separation scheme based on ion-exchange chromatography which has been used to separate the chromium- containing fractions in brewer's yeast, [S.J. Haylock, P.D. B...

In the absence of NAD+, up to 12 SH groups on aldehyde dehydrogenase (ALDH) reacted rapidly with p-(chloromercuri)benzoate (PCMB); a slow reaction with more than twice this number of SH groups then occurred. When PCMB was added to an assay mixture at low (less than 100 microM) concentrations of propionaldehyde, the steady-state rate of production o...

Die oktaedrischen Aminosäure-Cr(III)-Komplexe (I)-(III) werden nach bekannten Methoden synthetisiert und ihre Strukturen auf der Grundlage ihrer chromatographischen und spektroskopischen Eigenschaften angenommen.

A number of octahedral chromium complexes with amino acids are ligands have been prepared and their structures assigned on the basis of their chromatographic and spectral properties. These include complexes with the general structure Cr(AA)2(H2O)2 where the amino acids glycine, glutamic acid and glutamine act as bidentate ligands. The analogous com...

Cr(III)-Ionen, dargestellt aus wäßrigen Cr(III)- Ionen-Lösungen an einer Zn-Amalgam-Säule unter H,-Atmosphäre, reagieren mit Nicotinsäure unter H, zu dem N-koordinierten Cr(II)-Komplex (Ia) (RG C2 mit Z=2).

A series of N-coordinated M(II)(nic)2(H2O)4≠ complexes, where M = Co, Ni, Mn or Cr and the O-coordinated species Cr(III)(nic)2(H2O)4+ and Cr(III)(nic)(H2O)5+2 have been prepared. A single crystal X-ray analysis of the complex Cr(II)(nic)2(H2O)4 shows that the chromium ion is in the +2 oxidation state and that two nicotinic acid ligands are coordina...

After incubation with CrCl3 X 6H2O (or 51CrCl3 X 6H2O) for 25 days, a sterile growth medium, whole yeast cells harvested after growth on a similar chromium-containing medium for the same period, and the spent growth medium remaining after removal of the yeast were each subjected to the separation procedure reported previously [S. J. Haylock. P. D....

In order to account for the low amplitude burst in 4-nitrophenoxide production (0.2-0.3 mol per dehydrogenase active site) observed during the transient phase of the esterase catalytic pathway of cytoplasmic aldehyde dehydrogenase (E) from sheep liver with 4-nitrophenyl acetate (PNPA) as substrate, an equilibrium between E-PNPA and E·acyl complexes...

A procedure has been developed, based on ion-exchange chromatography, that readily allows the separation of eleven apparently homogeneous chromium-containing fractions from a brewer's yeast extract. Four of the fractions are amphoteric and show no glucose tolerance factor (GTF) activity, three are classified as negative (two of which are biological...

Magnesium chloride caused inhibition of the dehydrogenase activity of sheep liver cytoplasmic aldehyde dehydrogenase at all concentrations between pH 6 and 8 with no increase in the number of functioning subunits. There was also no decrease in the molecular weight as determined by gel filtration and laser light scattering experiments, results which...

Although aldehyde dehydrogenase (ALDH) from sheep liver cytosol has a broad specificity, it will not oxidize the aldehyde group of glyoxylic acid which is in fact an inhibitor of the enzyme. The inhibition pattern is non-linear but competitive at high propionaldehyde concentrations (2-20 mM); however, a simple non-competitive pattern is observed at...

The rate of carbon dioxide evolution by whole yeast cells was measured under conditions of both chromium starvation and availability. Preincubation experiments show that there is no evidence for the view thatSaccharomyces cerevisiae can synthesize a biologically important form of chromium from simple chromium(III) salts. Chromium enters the yeast c...

A transient release of protons with an amplitude corresponding to one proton per active site has been observed for the oxidation of propionaldehyde, acetaldehyde, and benzaldehyde by sheep liver cytoplasmic aldehyde dehydrogenase at pH 7.6 with phenol red as indicator. At saturating substrate levels, the rate constants for the proton burst are in e...

Cytoplasmic aldehyde dehydrogenase was shown to be free of contamination by the mitochondrial enzyme by isoelectric focusing. Both enzymes showed multiple banding in activity stains. The cytoplasmic enzyme gave two very close bands pl = 5.22 ± 0.03 whereas the mitochondrial enzyme showed seven bands, a pair at pl = 5.22 and five further bands of pl...

Sheep liver cytoplasmic aldehyde dehydrogenase was purified to homogeneity to give a sample with a specific activity of 380 nmol NADH min(-1) mg(-1). An amino acid analysis of the enzyme gave results similar to those reported for aldehyde dehydrogenases from other sources. The isoelectric point was at pH 5.25 and the enzyme contained no significant...

Kinetic studies were carried out on mitochondrial aldehyde dehydrogenase (EC 1.2.1.3) isolated from sheep liver. Steady-state studies over a wide range of acetaldehyde concentrations gave a non-linear double-reciprocal plot. The dissociation of NADH from the enzyme was a biphasic process with decay constants 0.6s-1 and 0.09s-1. Pre-steady-state kin...

The hydrolysis of 4-nitrophenyl acetate catalysed by cytoplasmic aldehyde dehydrogenase (EC 1.2.1.3) from sheep liver was studied by steady-state and transient kinetic techniques. NAD+ and NADH stimulated the steady-state rate of ester hydrolysis at concentrations expected on the basis of their Michaelis constants from the dehydrogenase reaction. A...

Stopped-flow experiments in which sheep liver cytoplasmic aldehyde dehydrogenase (EC 1.2.1.3) was rapidly mixed with NAD(+) and aldehyde showed a burst of NADH formation, followed by a slower steady-state turnover. The kinetic data obtained when the relative concentrations and orders of mixing of NAD(+) and propionaldehyde with the enzyme were vari...

The displacement of NADH from cytoplasmic aldehyde dehydrogenase (EC 1.2.1.3) from sheep liver was studied by using NAD+, 1,10-phenanthroline, ADP-ribose, deamino-NAD+ and pyridine-3-aldehyde-adenine dinucleotide as displacing agents, by following the decrease in fluorescence as a function of time. The data obtained could be fitted by assuming two...

1. Sheep liver cytoplasmic aldehyde dehydrogenase showed little pH dependence of V or kcat. Some buffer anion effects were noted. 2. The oxidation of aldehydes at pH 7.6 was quantitative but irreversible. The initial velocity data indicated a sequential mechanism for the addition of substrates. Inhibition by NADH and the product analogue 2-bromo-2-...

The effect of added dimethyl sulphoxide (Me2SO) on the primary deuterium kinetic isotope effect for NaOH-catalysed β-elimination from (p-acetylphenethyl)dimethylsulphonium bromide has been measured over the range 6–70 mol %. Despite the large increase in reaction rate, no significant maximum in the isotope effect was observed. Substituent induced c...

Correlations between 1H substituent-induced chemical shifts (scs) for α- and β-methylene protons in, and rate constants for base-catalysed E2 elimination from, substituted phenethyl bromides and dimethyl(phenethyl)sulphonium bromides have been obtained. The slopes of the best-fit straight lines were similar in all cases for the β-methylene protons...

Correlations between ¹³C substituent-induced chemical shifts (scs) for carbon atoms in substituted phenethyl bromides, dimethylphenethylsulphonium bromides and ethylbenzenes have been examined. C1 ¹³C scs were found to correlate with Hammett D values as expected from previous results with ¹H scs. The β-carbons showed no correlation while the α-carb...

Rate constants have been determined from the NaOH-catalysed 1,2-elimination of HBr from p-acetyl- and p-nitro-phenethyl bromide over a range of dimethyl sulphoxide concentrations. The calculated K2H/K2D ratios show no dependence on the para-substituent or the dimethyl sulphoxide concentration except for p-nitrophenethyl bromide at 59.7 and 69.7 mol...

The oxidation of a series of primary alcohols by liver alcohol dehydrogenase has been studied under conditions of [S]o greater than [E]o using the stopped-flow method. A biphasic process, with exponential rise to a steady state, was observed for most of the alcohols and the rate constants for the transient phase were determined. No transient phase...

Primary deuterium kinetic isotope effects (K2H/K2D) have been determined for 1,2-elimination from a series of substituted phenethyl bromides and dimethyl(phenethyl)sulphonium bromides in 50·2 mole % Me2SO–H2O. A maximum in the K2H/K2D ratio was observed for the phenethyl bromides but the existence of a maximum could not be determined for the dimeth...

The oxidation of benzyl alcohols by liver alcohol dehydrogenase under conditions [S] 0 ≫ [E] 0 is a biphasic process with exponential rise to a steady state. The rate constants for the transient phase were determined by a curve‐fitting procedure. A large isotope effect was obtained for p ‐methoxybenzyl alcohol, indicating that hydrogen transfer is...

Contrary to our predictions, premixing of enzyme with NAD has little effect on the transient phase of the oxidation of ethanol by liver alcohol dehydrogenase. This observation has led us to re-examine the theory of premixing effects and to consider the consequences of this theory for the reduction of aldehydes by alcohol dehydrogenase.

Deuterium kinetic isotope effects (k2H/k2D) have been measured for the elimination of HBr from a series of substituted phenethyl bromides. No variation in the magnitude of the isotope effect was observed. The k2H values have been correlated by the Hammett equation to give ρ= 2·85. Some evidence for proton tunnelling has been obtained.

The self-association of pyrrolid-2-one has been studied in CDCl3 and CD3CN at several temperatures by the use of high resolution nuclear magnetic resonance spectroscopy. The enthalpies of self-association of the lactam in the two solvents have been measured and are in reasonable agreement with those for similar systems determined by the use of othe...