Frank Heckel

Publications of Frank Heckel

• Direct trapping of formaldehyde formed via oxidative N-demethylation of N,N-dialkylarylamines by Bacillus megaterium using cysteamine derivatization.

  Authors: Marcus Taupp, Frank Heckel, Dag Harmsen, Peter Schreier

  Journal of microbiological methods. 12/2006; 67(2):357-62.

  Oxidative N-demethylation was measured by incubation experiments using Bacillus megaterium isolated from topsoil as a biocatalyst for the N-demethylation of the N,N-dialkylarylaminesOxidative N-demethylation was measured by incubation experiments using Bacillus megaterium isolated from topsoil as a biocatalyst for the N-demethylation of the N,N-dialkylarylamines N,N-dimethylaniline and N-ethyl-N-methylaniline. Formed formaldehyde, normally difficult to analyse in biological systems because of further metabolization, was successfully trapped and converted into thiazolidine by addition of cysteamine into the incubation media. Studies using N,N-di-(trideutero-methyl)-aniline and N-ethyl-N-(trideuteromethyl)-aniline as well as N,N-di-[methyl-(13)C]-aniline and N-ethyl-N-[methyl-(13)C]-aniline were performed to confirm that the N-demethylation proceeds via formaldehyde.

• Production of natural methyl anthranilate by microbial N-demethylation of N-methyl methyl anthranilate by the topsoil-isolated bacterium Bacillus megaterium.

  Authors: Marcus Taupp, Dag Harmsen, Frank Heckel, Peter Schreier

  Journal of agricultural and food chemistry. 12/2005; 53(24):9586-9.

  Bacillus megaterium, isolated in a screening process from topsoil, was used for N-demethylation of natural N-methyl methyl anthranilate to produce natural methyl anthranilate. Maximal productivity ofBacillus megaterium, isolated in a screening process from topsoil, was used for N-demethylation of natural N-methyl methyl anthranilate to produce natural methyl anthranilate. Maximal productivity of 70 mg/L/day was achieved under laboratory-scale conditions without further optimization. No byproducts were observed. Thus, production of "natural" methyl anthranilate using B. megaterium is a significant improvement over comparable already existing procedures.

• Opposite enantioselectivities of two phenotypically and genotypically similar strains of Pseudomonas frederiksbergensis in bacterial whole-cell sulfoxidation.

  Authors: Waldemar Adam, Frank Heckel, Chantu R Saha-Möller, Marcus Taupp, Jean-Marie Meyer, Peter Schreier

  Applied and environmental microbiology. 05/2005; 71(4):2199-202.

  Soil samples were screened to select microorganisms with the capability to oxidize organic sulfides into the corresponding sulfoxides with differential enantioselectivities. Several bacterial strainsSoil samples were screened to select microorganisms with the capability to oxidize organic sulfides into the corresponding sulfoxides with differential enantioselectivities. Several bacterial strains that preferentially produced the S-configured sulfoxide enantiomer were isolated. Surprisingly, one bacterial strain, genotypically and phenotypically characterized as Pseudomonas frederiksbergensis, selectively gave the R enantiomer. The finding that two apparently identical organisms displayed opposite enantioselectivities is novel for non-genetically modified organisms.

• Determination of 2H/1H and 13C/12C isotope ratios of (E)-methyl cinnamate from different sources using isotope ratio mass spectrometry.

  Authors: Kathrin Fink, Elke Richling, Frank Heckel, Peter Schreier

  Journal of agricultural and food chemistry. 06/2004; 52(10):3065-8.

  For the authenticity assessment of (E)-methyl cinnamate from different origins, combustion/pyrolysis-isotope ratio mass spectrometry (C/P-IRMS) was used by an elemental analyzer (EA) and on-lineFor the authenticity assessment of (E)-methyl cinnamate from different origins, combustion/pyrolysis-isotope ratio mass spectrometry (C/P-IRMS) was used by an elemental analyzer (EA) and on-line capillary gas chromatography coupling (HRGC-C/P-IRMS). For that reason, (E)-methyl cinnamate self-prepared from synthetic, natural, and semisynthetic educts was analyzed in comparison to the commercial synthetic and natural ester. In addition, (E)-methyl cinnamate from basil extract and a number of commercial natural aromas was investigated. The data of self-synthesized synthetic (E)-methyl cinnamate, i.e., delta(13)C(V)(-)(PDB) = -33.8 per thousand and delta(2)H(V)(-)(SMOW) = +349 per thousand, corresponded with that found for the commercial synthetic samples (-29.5 to -31.4 per thousand and +328 to +360 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively). The ester produced from natural educts by acid as well as Candida antarctica catalysis revealed delta(13)C(V)(-)(PDB) = -25.6 and -30.1 per thousand as well as delta(2)H(V)(-)(SMOW) = -162 and -169 per thousand, respectively. Acid-catalyzed semisynthetic products differed in their delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) values depending on the origin of their educts. For the ester from synthetic methanol and natural cinnamic acid, -27.3 and -126 per thousand were determined for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively, whereas for the ester produced from natural methanol and synthetic acid delta(13)C(V)(-)(PDB) = -30.6 per thousand and delta(2)H(V)(-)(SMOW) = +287 per thousand were found. Basil extract showed -28.9 and -133 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively. Commercial aromas declared to be natural revealed delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data ranging from -25.7 to -28.5 per thousand as well as -85 to -191 per thousand, respectively, indicating, in part, incorrect declaration.

• On-line gas chromatography combustion/pyrolysis isotope ratio mass spectrometry (HRGC-C/P-IRMS) of pineapple (Ananas comosus L. Merr.) volatiles.

  Authors: Christina Preston, Elke Richling, Sandra Elss, Markus Appel, Frank Heckel, Ariane Hartlieb, Peter Schreier

  Journal of agricultural and food chemistry. 01/2004; 51(27):8027-31.

  By use of extracts prepared by liquid-liquid separation of the volatiles from self-prepared juices of pineapple fruits (Ananas comosus) (n = 14) as well as commercial pineapple recovery aromas/waterBy use of extracts prepared by liquid-liquid separation of the volatiles from self-prepared juices of pineapple fruits (Ananas comosus) (n = 14) as well as commercial pineapple recovery aromas/water phases (n = 3), on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta(13)C(VPDB) and delta(2)H(VSMOW) values of selected pineapple flavor constituents. In addition to methyl 2-methylbutanoate 1, ethyl 2-methylbutanoate 2, methyl hexanoate 3, ethyl hexanoate 4, and 2,5-dimethyl-4-methoxy-3[2H]-furanone 5, each originating from the fruit, the delta(13)C(VPDB) and delta(2)H(VSMOW) data of commercial synthetic 1-5 and "natural" (biotechnologically derived) 1-4 were determined. With delta(13)C(VPDB) data of pineapple volatiles 1-4 varying from -12.8 to -24.4 per thousand, the range expected for CAM metabolism was observed. Compound 5 showed higher depletion from -20.9 to -28.6 per thousand. A similar situation was given for the delta(2)H(VSMOW) values of 3-5 from pineapple ranging from -118 to -191 per thousand, whereas 1 and 2 showed higher depleted values from -184 to -263 per thousand. In nearly all cases, analytical differentiation of 1-5 from pineapple and natural as well as synthetic origin was possible. In general, natural and synthetic 1-5 exhibited delta(13)C(VPDB) data ranging from -11.8 to -32.2 per thousand and -22.7 to -35.9 per thousand, respectively. Their delta(2)H(VSMOW) data were in the range from -242 to -323 per thousand and -49 to -163 per thousand, respectively.

• (S)-2,3-dihydrofarnesoic acid, a new component in cephalic glands of male European beewolves Philanthus triangulum.

  Authors: Thomas Schmitt, Erhard Strohm, Gudrun Herzner, Carlo Bicchi, Gerhard Krammer, Frank Heckel, Peter Schreier

  Journal of chemical ecology. 12/2003; 29(11):2469-79.

  The chemical composition and functional significance of pheromones of solitary Hymenoptera is much less well known compared to social species. Males of the genus Philanthus (Sphecidae) areThe chemical composition and functional significance of pheromones of solitary Hymenoptera is much less well known compared to social species. Males of the genus Philanthus (Sphecidae) are territorial and scent mark their territories to attract females. Because of inconsistent results of earlier studies, we reanalyzed the content of the cephalic glands of male European beewolves, Philanthus triangulum F. Besides a variety of alkanes and alkenes, four major compounds were found. Two of these, (Z)-11-eicosen-1-ol and (Z)-10-nonadecen-2-one, had been previously described as constituents of the cephalic glands. We identified 1-octadecanol as a new component of the cephalic gland, and a fourth compound, enantiopure (S)-2,3-dihydrofamesoic acid, was identified for the first time in nature. Structural elucidation and enantiomeric analysis were performed by HRGC-MS and HRGC-FTIR as well as enantioselective gas chromatography and by means of authentic reference compounds. Occurrence and function of the four compounds in insect chemistry are discussed.

• Tequila authenticity assessment by headspace SPME-HRGC-IRMS analysis of 13C/12C and 18O/16O ratios of ethanol.

  Authors: Blanca O Aguilar-Cisneros, Mercedes G López, Elke Richling, Frank Heckel, Peter Schreier

  Journal of agricultural and food chemistry. 01/2003; 50(26):7520-3.

  By use of headspace SPME sampling and a PLOT column, on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modesBy use of headspace SPME sampling and a PLOT column, on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta(13)C(VPDB) and delta(18)O(VSMOW) values of ethanol in authentic (n = 14) and commercial tequila samples (n = 15) as well as a number of other spirits (n = 23). Whereas with delta(13)C(VPDB) values ranging from -12.1 to -13.2 per thousand and from -12.5 to -14.8 per thousand similar variations were found for 100% agave and mixed tequilas, respectively, the delta(18)O(VSMOW) data differed slightly within these categories: ranges from +22.1 to +22.8 per thousand and +20.8 to +21.7 per thousand were determined for both the authentic 100% agave and mixed products, respectively. The data recorded for commercial tequilas were less homogeneous; delta(13)C(VPDB) data from -10.6 to -13.9 per thousand and delta(18)O(VSMOW) values from +15.5 to +22.7 per thousand were determined in tequilas of both categories. Owing to overlapping data, attempts to differentiate between white, rested, and aged tequilas within each of the two categories failed. In addition, discrimination of tequila samples from other spirits by means of delta(13)C(VPDB) and delta(18)O(VSMOW) data of ethanol was restricted to the products originating from C(3) as well as C(4)/CAM raw materials.

• Selective (R)-3-hydroxylation of FA by Stenotrophomonas maltophilia.

  Authors: Kerstin Weil, Patrick Gruber, Frank Heckel, Dag Harmsen, Peter Schreier

  Lipids. 04/2002; 37(3):317-23.

  Soil samples were screened for microorganisms selectively transforming FA. One of the isolated strains was identified as the bacterium Stenotrophomonas maltophilia by its phenotypic features andSoil samples were screened for microorganisms selectively transforming FA. One of the isolated strains was identified as the bacterium Stenotrophomonas maltophilia by its phenotypic features and genotypic characterization by sequencing the ribosomal RNA gene. Using linoleic acid as substrate resulted in the formation of two major compounds. After liquid chromatographic isolation and separation, their structures were elucidated by HPLC-tandem MS, GC-MS, and NMR techniques to be 3-hydroxy-Z6-dodecenoic acid and 3-hydroxy-Z5,Z8-tetradecadienoic acid. In additional experiments, other FA, such as a-linolenic, oleic, palmitoleic, myristoleic, and cis-vaccenic acids, were converted to 3-hydroxylated metabolites of shorter chain lengths as well. Determination of the enantiomeric composition revealed highly enriched (R)-hydroxylation (88-98% enantiomeric excess).

• On-line gas chromatography combustion/pyrolysis isotope ratio mass spectrometry (HRGC-C/P-IRMS) of major volatiles from pear fruit (Pyrus communis) and pear products

  Authors: Kathrin Kahle, Christina Preston, Elke Richling, Frank Heckel, Peter Schreier

  Food Chemistry.

  Using extracts obtained by simultaneous distillation extraction (SDE) as well as liquid liquid extraction (LLE) of self-prepared juices from pear fruits (n = 20) and from commercial pear productsUsing extracts obtained by simultaneous distillation extraction (SDE) as well as liquid liquid extraction (LLE) of self-prepared juices from pear fruits (n = 20) and from commercial pear products (juices, n = 11; brandies, n = 16; baby food, n = 8), on-line capillary gas chromatography–isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the δ13CV-PDB and δ2HV-SMOW values of major pear flavour constituents. In addition to butyl acetate 1, 1-butanol 2, hexyl acetate 3, 1-hexanol 4, as well as the ‘pear esters’ methyl E,Z-2,4-decadienoate 5, ethyl E,Z-2,4-decadienaote 6, and ethyl E,E-2,4-decadienoate 7, each originating from the fruit, the δ13CVPDB and δ2HV-SMOW data of commercial synthetic and “natural” (biotechnologically derived) 1–7 were determined.

• Direct trapping of formaldehyde formed via oxidative N-demethylation of N,N-dialkylarylamines by Bacillus megaterium using cysteamine derivatization

  Authors: Marcus Taupp, Frank Heckel, Dag Harmsen, Peter Schreier

  Journal of Microbiological Methods.

  Oxidative N-demethylation was measured by incubation experiments using Bacillus megaterium isolated from topsoil as a biocatalyst for the N-demethylation of the N,N-dialkylarylaminesOxidative N-demethylation was measured by incubation experiments using Bacillus megaterium isolated from topsoil as a biocatalyst for the N-demethylation of the N,N-dialkylarylamines N,N-dimethylaniline and N-ethyl-N-methylaniline. Formed formaldehyde, normally difficult to analyse in biological systems because of further metabolization, was successfully trapped and converted into thiazolidine by addition of cysteamine into the incubation media. Studies using N,N-di-(trideutero-methyl)-aniline and N-ethyl-N-(trideuteromethyl)-aniline as well as N,N-di-[methyl-13C]-aniline and N-ethyl-N-[methyl-13C]-aniline were performed to confirm that the N-demethylation proceeds via formaldehyde.

• Biohydroxylation of N,N-dialkylarylamines by the isolated topsoil bacterium Bacillus megaterium

  Authors: Marcus Taupp, Frank Heckel, Dag Harmsen, Peter Schreier

  Enzyme and Microbial Technology.

  Topsoil microorganisms were screened for their acceptability of the standard substrate N,N-dimethylaniline in bacterial ‘whole-cell’ incubations. One bacterium converted N,N-dimethylaniline and wasTopsoil microorganisms were screened for their acceptability of the standard substrate N,N-dimethylaniline in bacterial ‘whole-cell’ incubations. One bacterium converted N,N-dimethylaniline and was identified as Bacillus megaterium by 16S rDNA analysis and DNA/DNA-hybridization. In contrast to the well-known C-hydroxylation by liver microsomes, leading to p-hydroxylation, B. megaterium formed o- and p-monohydroxylated products, i.e. N,N-dimethyl-2-aminophenol and N,N-dimethyl-4-aminophenol, both identified by gas chromatography–mass spectrometry (GC–MS) using synthesized reference compounds. The observed hydroxylation showed slight regioselectivity in favour of the o-hydroxylated product. Two further substrates, N,N-diethylaniline and N-ethyl-N-methylaniline, were also successfully biohydroxylated by B. megaterium with corresponding regioselectivity. Interestingly, aniline, known to be transformed easily by cytochrome P-450meg into p-aminophenol, was not accepted as substrate.