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D ‐Lysine, alloisoleucine and lysinoalanine in supplementary proteins with different lysine availabilities
Author(s) -
Davies Richard L
Publication year - 1993
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740610203
Subject(s) - lysine , chemistry , food science , hydrolysis , isoleucine , bioavailability , biochemistry , amino acid , biology , leucine , pharmacology
D ‐Lysine, alloisoleucine and lysinoalanine were determined in 16 commercial protein supplements on which lysine availability had been measured by slope‐ratio assay with pigs and by chemical dinitrophenylation. About 2.5% of lysine was racemised by protein hydrolysis in 6 M HCl. Only three of 10 samples with poor lysine availability by slope‐ratio assay contained significantly more D ‐iysine than control proteins ( P < 0.01). D ‐Lysine was not significantly correlated with lysine availability by either method; nor did it improve the poor correlation between the slope‐ratio assay and dinitrophenylation. The highest level of alloisoleucine was less than 14% that of isoleucine. In all proteins except skim milk powder lysinoalanine occurred at 0.3% or less of the corresponding lysine level. Neither alloisoleucine nor lysinoalanine was related to lysine availability.