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Biomedical subjects

W Grosch

Publications and source records attributed to W Grosch.

At least 37 records · Page 2Linked to original sources
PubMed1981

A study of oxygen isotope scrambling in the enzymic and non-enzymic oxidation of linoleic acid.

Lipoxygenases-1 and -2 isolated from soybeans were incubated with linoleic acid in the presence of a mixture of 16O2 and 18O2. The formation of 16O/18O-molecules which is indicative for a head-to head reaction of peroxy radicals was determined and compared with that produced during autoxidation of a linoleic acid emulsion in the presence of ferric ions. Lipoxygenase-1 was much less active in scrambling than lipoxygenase-2 which was comparable to that found in the autoxidation reaction.

Isoenzymes↗
PubMed1979

Co-oxidation of carotenes requires one soybean lipoxygenase isoenzyme.

The type II lipoxygenase (optimum pH 6.5) from soybeans was purified and separated into two fractions either by chromatography on DEAE-Sephadex or by isoelectric focusing. In the presence of linoleic acid and oxygen both fractions co-oxidise canthaxanthine or beta-carotene as effectively as a combination of these fractions. Oxygenation of linoleic acid and co-oxidation of canthaxanthine by type II lipoxygenase is stimulated by 13-hydroperoxy-cis-9,trans-11-octadecadienoic acid but not by 13-hydroxy-cis-9,trans-11-octadecadienoic acid or 9-hydroperoxy-trans-10,cis-12-octadecadienoic acid.

Carotenoids↗
PubMed1978

[Lipoxygenases from pears, strawberries and gooseberries: partial purification and properties (author's transl)].

Membrane-bound lipoxygenases (EC 1.13.11.12) were partially purified from the fruits by centrifugation and gel chromatography. The enzymes have a pH-optimum at 6.0 (pear) resp. 6.5 (strawberry, gooseberry). Linoleic acid is oxidised to 9- and 13-hydroperoxides in a ratio of 3:7 (pear), 2:8 (strawberry) and 1:1 (gooseberry). The enzymes from gooseberries and from strawberries co-oxidise canthaxanthine with a higher specific activity than the lipoxygenases from pears and apples.

Fruit↗
PubMed1978

[Determination of reduced and oxidised glutathione in wheat flours and doughs (author's transl)].

A quantitative method for the analysis of reduced (GSH) and oxidised (GSSG) glutathione in cereals has been developed. The steps are: Extraction of the flour or dough and carboxymethylation of GSH, gel filtration on Sephadex G-50, chromatography on Dowex 50 WX8 and after basic cleavage determination of the separated GSSG with 5,5'-dithiobis(2-nitrobenzoic acid), separation of carboxymethylated GSH on Dowex 1X8 and determination with 2,4,6-trinitrobenzenesulfonic acid. When analysing for the amount of GSH and GSSG in flours of three varieties of wheat the former ranged from 0.27 to 0.46 mumol/g and the latter from 0.26 to 0.38 mumol/g. After kneading for 5 min to a dough the GSH disappeared with a corresponding increase in GSSG.

Chromatography↗
PubMed1977

[Co-oxydation of linoleic acid to volatile compounds by lipoxygenase isoenzymes from soya beans (author's transl)].

Lipoxygenase isoenzymes L-1 (optimum pH 9.0) and L-2 (pH 6.5) were incubated with linoleic acid. The extracted volatile compounds were separated by gas-chromatography and analysed by mass spectrometry. The relative amounts of volatile carbonyl compounds, which were formed during catalysis were determined (mole percent). L-1 yielded hexanal (greater than 90% at pH 7 and 70% at pH 8.5). L-2 at pH 7 yielded hexanal (31), two geometric isomers of 2,4-decadienal (40), 2-trans-heptenal (12) and 2-trans-octenal (10).

Isoenzymes↗
PubMed1977

[Co-oxidation of beta-carotene and canthaxanthine by purified lipoxygenases from soya beans (author's transl)].

Isolation and purification of soya bean lipoxygenase (linoleate: O2 oxidoreductase, EC, 1.13.11.12) on Sephadex G-200, DEAE-cellulose and by isolectric focusing yields two isoenzymes of the L- 2 type (optimum pH 6.5) and two of the L-1 type (optimum pH9.0). Different crude extracts from soya beans as well as the purified L-2 isoenzymes exhibit the same capacity for co-oxidation of beta-carotene and canthaxanthine, when the comparison is based upon equal lipoxygenase activities. In contrast to L-2 the alkaline lipoxygenase L-1 is a poor "carotene oxidase".

Carotenoids↗
PubMed1977

[Investigation about the taste of di, tri- and tetrahydroxy fatty acid].

Two diastereomeric 9, 10-dihydroxystearic acids, four diasteromeric 9,10,12-trishydroxystearic acids, a mixture of diastereomeric 9,10,12,13-tetrahydroxystearic acids, a mixture of 9.12,13,-trihydroxy-10 trans- and 9,10,13-trihydroxy-11-trans-octadecenoic acids (tri-OH-mixture from lipoxygenase catalysis) and the hydrogenated tri-OH mixture were tested for bitter taste. Only the tri - and tetrahydroxy acids are bitter. The taste thresholds of the saturated tri- and tetrahydroxy acids are in the range from 1.0--4.3 micron ol/ml. There are no significant differences in the taste thresholds between the four diastereomeric 9,- 10,12-trihydroxy acids. The double bond in the trihydroxy acids from the lipoxygenase catalysis enhances the bitter taste 3-fold.

Humans↗
PubMed1977

Enzymatic oxydation of linoleic acid: formation of bittertasting fatty acids.

Linoleic acid was oxidized with a protein fraction from soya beans (25 degrees C; 2h), in which lipoxygenase and peroxydase activities occurred. The fatty acids formed were isolated and, after emulsification with a sugar ester, were evaluated for bitter taste. The main components of the bitter-tasting fractions was a mixture of 9.12.13-trihydroxyoctadec-10- and 9.10.13-trihydroxyoctadec-11-enoic acids. The taste threshold lies in the range 0.6-0.9 mumol/ml. Two further trihydroxy-acids and two oxodihydroxy-acids were also identified in the bitter-tasting fraction.

Fatty Acids↗
PubMed1977

[Positional specificity of the peroxidation of linoleic and linolenic acid by homogenates from apples and pears (author's transl)].

Homogenates of apples and pears were incubated (25 degrees C, 20 min) with linoleic and linolenic acid. The major products were fatty acid hydroperoxides. The ratio of 13- to 9-hydroperoxides were at least 82:18 in favour of the 13-isomer for apples and 10:90 in favour of the 9-isomer for pears. The significance of the results for the formation of flavour compounds in apples and pears is discussed.

Aldehydes↗
PubMed1977

[Breakdown of linoleic and linolenic acid hydroperoxides in the presence of ascorbic acid analysis of the volatile aldehydes (author's transl)].

Hydroperoxide emulsions with 10(-3) mol ascorbic acid were stored for 19 h at 22 degrees C. Volatile aldehydes were formed in the presence of oxygen and traces of metals. The main compounds were identified as follows (mol-%): 2-pentenal [51] and 2-hexenal [22] from 13-hydroperoxioctadeca-9,11,15-trienoic acid; propanol [38] and 2-hexenal [25] from 9-hydroperoxioctadeca-10,12,15-trienoic acid; hexanal [82] respectively [66] from 13-hydroperoxioctadeca-9,11-respectively 9-hydroperoxioctadeca-10,12-dienoic acid. C9 and C10 aldehydes were only detected in very low concentrations as fragments of the 9-hydroperoxides.

Aldehydes↗
PubMed1976

[Glutathatione-dehydrogenase of wheat flour. Purification and properties (author's transl)].

Glutathione: dehydroascorbic acid oxidoreductase (EC 1.8.5.1) has been purified to essential homogeneity by precipitation with (NH4)2SO4, and ion-exchange chromatography on CM-Sephadex and DEAE-cellulose. The molecular weight is 24200 Dalton as determined by SDS-PAG-electrophoresis. The amino acid composition was analysed. The esed. The enzyme ist specific for glutathione as H-donor and it reduces the L-threo-diasteromer faster than the L-erythro- and D-erythro-dehydroascorbic acid. The enzyme is inhibited by iode acetic acid and N-ethyl-maleinimide. Zero-order kinetics was only observed for the hydrogen-acceptor but not for glutathione.

Oxidoreductases↗
PubMed1976

[Breakdown of linoeic acid hydroperoxydes. Formation of volatile carbonyl compounds (author's transl)].

Linoleic acid hydroperoxydes (LOOH) containing 13-hydroperoxyoctadeca-9,11-(75%) and 9-hydroperoxyoctadeca-10,12-dienoic acid (25%) were emulsified at pH 6.5. After addition of hemoglobin, ferrous ions, ferric ions, cysteine or ascorbic acid the emulsions were stored 19 hours at 22 degrees C. The decrease in the diene and peroxyde concentrations and the formation of volatile carbonyl compounds were analysed. Ferrous ions and ascorbic acid were the strongest producers of volatile carbonyl compounds. In the presence of 10(-3) Mol ascorbic acid 6 mumol volatile aldehydes arise from 75 mumol LOOH. Hexanal (70 mol-%) was the main component of the aldehyde fraction. For plant foodstuffs the significance of the reaction of fatty acids hydroperoxydes with ascorbic acid for the formation of flavour substances is discussed.

Aldehydes↗
PubMed1976

Co-oxydation of a carotenoid by the enzyme lipoxygenase: influence on the formation of linoleic acid hydroperoxides.

A partially purified soybean lipoxygenase (L-3) was incubated for 15 min at pH 6.5 with linoleic acid and oxygen. Systems with and without the polyene glycoside crocin were compared. The system with crocin reacted with higher velocity with oxygen than did the control experiment without polyene. From the crocin 40% was destroyed. In the presence of crocin about 40% more linoleic acid hydroperoxides was formed than without the polyene but the linoleic acid break-down was equal in both experiments. L-3 peroxidises linoleic acid to 13L:13D:9L:9D-hydroperoxides in the proportions 43:11:21:25. In the presence of crocin the ratio of the isomers changed to 64:11:11:14.

Carotenoids↗
PubMed1975

[Microbes from soya beans. Inhibition of growth by lipoxygenase isoenzyme].

Sixteen fungi and fife bacteria were isolated from soya beans and their species were determined. The microorganisms were cultivated on soya flour agar plates sterilized by heat. After addition of an enriched lipoxigenase preparation the growth was followed. The fungi but not the bacteria were all, to a varying degree, inhibited. Obviously the lipoxygenase peroxidizes the substrates occuring in the soya flour to compounds that inhibit the growth of the fungi.

Bacteria↗
PubMed1975

[Determination of GSH-DH activity (E.C.1.8.5.1) presence of the enzyme in different wheat varieties (author's transl)].

2,6-dichlorophenol-indophenol is more stable in 75% ethanol than in aqueous solution and ascorbic acid reacts considerably faster in this media than glutathione. The activity determination of glutathione: dehydroascorbic acid oxidoreductase was based on these observations by a photometric measurement of the ascorbic acid resulting from the catalysis. Extracts from various types of wheat were tested and relatively high enzyme activities were found.

Ascorbic Acid↗