Disulphide bonds in wheat gluten: isolation of a cystine peptide from glutenin.
Gluten from the wheat variety Rektor was extracted with 70% aqueous ethanol. The residual protein (glutenin) was hydrolysed with trypsin. The partial hydrolysate was separated into seven fractions by gel permeation chromatography on Sephadex G 25. Four cystine-containing peptides were isolated from fraction 5 by reversed-phase high-performance liquid chromatography on ODS-Hypersil. The cystine peptides were detected by differential chromatography of the non-reduced and the reduced samples. The primary structure of the peptides was solved by the Edman degradation reaction and by partial hydrolysis with thermolysin. Three peptides derive from the alpha 2- and beta-purothionins. The structure of the fourth peptide was determined as (Formula; see text) This sequence corresponds to positions 44-48 of known sequences of the high molecular weight (HMW) subunits 9, 10, and 12. Since Rektor contains the HMW subunits 9 and 10, it could be concluded that two HMW subunits 9 or 10, or one subunit 9 and one subunit 10 were linked parallel via two disulphide bridges.
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Deutsche Forschungsanstalt für Lebensmittelchemie, München, Federal Republic of Germany.
Belitz
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Wieser
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D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003553:Cystine / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry*; D005983:Glutens / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D013820:Thermolysin / Q000378:metabolism; D014908:Triticum; D014357:Trypsin / Q000378:metabolism
D000596:Amino Acids; D004220:Disulfides; D010455:Peptides; D003553:Cystine; D005983:Glutens; D014357:Trypsin; D013820:Thermolysin; C037302:glutenin