Aggregation of peptides during hydrolysis as a cause of reduced enzymatic extractability of soybean meal proteins.
With the purpose of analyzing the size and composition of enzyme-unextractable proteins in differently heat-treated soybean meals, a selection of extractants was screened for their ability to extract these proteins from enzyme-unextractable residues. The largest effects were obtained with urea, urea plus beta-mercaptoethanol, and dilute alkali; the latter extracted up to 87% of the enzyme-unextractable protein. Gel permeation chromatography indicated that a large proportion of the extracted material was of high molecular weight. However, the combined results from gel electrophoresis, LC-MS, and MALDI-ToF MS showed that the extracted protein material was composed of aggregated peptides. The largest aggregates were observed in the enzymatic residues originating from meals heat-treated at high humidity. Extracted aggregates were fully degraded upon subsequent proteolytic treatment.
Fischer
Morten
M
Centre for Protein Technology TNO-WU, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Gruppen
Harry
H
Piersma
Sander R
SR
Kofod
Lene V
LV
Schols
Henk A
HA
Voragen
Alphons G J
AG
D000596:Amino Acids / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism*; D006358:Hot Temperature; D006813:Humidity; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D013058:Mass Spectrometry; D008623:Mercaptoethanol; D008970:Molecular Weight; D010455:Peptides / Q000378:metabolism*; D030262:Soybean Proteins / Q000302:isolation & purification* / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014508:Urea
D000596:Amino Acids; D002241:Carbohydrates; D010455:Peptides; D030262:Soybean Proteins; D008623:Mercaptoethanol; D014508:Urea; D010450:Endopeptidases