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ABSTRACT: Changes in structure of alpha1-acid glycoprotein were followed after deglycosylation with neuraminidase, peptide N-glycohydrolase F or with a mixture of exoglycosidases. Partially deglycosylated preparations of alpha1-acid glycoprotein free of sialic acids, one complete saccharide component, sialic acids and one saccharide component and sialic acids and some of the external saccharides were obtained. The effect of these changes in saccharide components on the glycoprotein structure was studied by temperature perturbation difference spectroscopy, fluorescence spectroscopy, fourth-derivative of absorption spectra and spectra of CD. Partial deglycosylation resulted in transformation of the molecule to a more compact state in which phenylalanyl residues were even more buried, tyrosyl residues became more uniform and tryptophyl residues were less exposed. The content of ordered secondary structures decreased. The thermal stability of the molecule was not significantly affected. Removal of one of the five saccharide components from the native molecule had apparently deeper effect than total desialyzation of the glycoprotein.
General Physiology and Biophysics 01/2000; 18(4):371-86. · 1.19 Impact Factor
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V Karpenko
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ABSTRACT: Three important doctrines of European alchemy are discussed: the Emerald Table of Hermes, the idea of transmutation, and the Elixir of Life. The analysis of these problems is focused on the 16th century, the epoch of the high flourish of alchemy in Renaissance Europe. As typical examples two works are chosen: the treatises of Jean-Pierre Fabre (1588-1658) and Alexander von Suchten (? 1520 - ? 1590). The arguments of these authors illustrate the ways how alchemists tried to defend their position in face of repeated failures. Just the 16th century stood in the sign of dramatic development of crafts, but, simultaneously, of growing interest in alchemy.
Bulletin of the Indian Institute of History of Medicine (Hyderabad) 02/1999; 29(1):63-70.
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ABSTRACT: The stability of Zn-alpha 2-glycoprotein has been studied using UV-spectroscopy and circular dichroism with respect to the influence of temperature, pH, and solvent composition. It has been found that: (1) this protein contains a relatively high proportion of beta-sheet (60%) and a very low amount of other periodic structures as estimated from circular dichroic spectra; (2) at pH 7.4, the circular dichroic spectra change reversibly in the temperature range between 25 and 85 degrees C; small disturbances were observed at 265 nm; (3) with the assumption of the two-state process, the temperature of cooperative denaturation was Tm = 66 degrees C, van't Hoff's enthalpy of this process was 27 kJ mol-1; (4) up to pH 9.5 the dichroic spectrum appeared the same as at pH 7.4; (5) in the presence of methanol (vol. fraction 50%), no isodichroic points on the circular dichroic spectra were found during temperature denaturation; after cooling from 85 degrees C, the alpha-helix content was higher than in the native protein; (6) in the molecule of Zn-alpha 2-glycoprotein, 14 out of 18 tyrosines can dissociate with the instrinsic pK = 11.2; and (7) the temperature perturbation difference spectra yielded nonlinear delta A vs. T curves with temperature transition corresponding to the values found in the circular dichroic spectra; the numbers of chromophores exposed to the solvent as determined by the temperature difference spectra were: 4 tyrosines, 1 tryptophan, and 1 phenylalanine. In several aspects, a parallel has been found between Zn-alpha 2-glycoprotein and orosomucoid (acid alpha 1-glycoprotein), another plasma glycoprotein.
Biophysical Chemistry 01/1998; 69(2-3):209-17. · 2.20 Impact Factor
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V Karpenko
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ABSTRACT: Medical trends in European alchemy are discussed. There existed a direction that in curing illnesses made use of various substances known to alchemists. The origin can be traced back to the 14th century and further development of this trend has later led to iatrochemistry. Beside this, there existed all the time the second direction called alchemical medicine. It searched for miraculous universal medicine using for this purpose approaches known from attempts in metal transmutation. Several examples of the confused world of alchemical medicine are brought.
Bulletin of the Indian Institute of History of Medicine (Hyderabad) 02/1995; 25(1-2):202-15.
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ABSTRACT: Heat denaturation of orosomucoid in solutions of methanol concentrations ranging from 0 to 70% (v/v) has been studied by using circular dichroism, intrinsic protein fluorescence and thermal difference absorption spectroscopy. Regardless of its high saccharide content (40%), the highly cooperative denaturation transition of orosomucoid is fully reversible in neutral water solution. A two-state model has been successfully applied; the numerical analysis results in thermodynamical parameter values that are in close agreement with previously reported experimental data from calorimetric measurements. However, in solutions containing even minute concentrations of methanol (5%) the heat denaturation is irreversible. After cooling of the denatured protein the refolded molecules exhibit a higher alpha-helical content than the native one. Possibilities of methanol interaction with native and denatured protein molecule are discussed.
Biochimica et Biophysica Acta 02/1995; 1246(1):10-6. · 4.66 Impact Factor
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V Karpenko
Bulletin of the Indian Institute of History of Medicine (Hyderabad) 08/1991; 21(2):105-19.
