Idendification of sulphur-rich proteins which resist rumen degradation and are hydrolysed rapidly by intestinal proteases

Autor: Kerrie R. Hancock, Paul M. Ealing, Derek W. R. White
Rok vydání: 1994
Předmět:
Zdroj: British Journal of Nutrition. 72:855-863
ISSN: 1475-2662
0007-1145
DOI: 10.1079/bjn19940090
Popis: Several proteins with high proportions of S-containing essential amino acids were incubated in sheep rumen fluidin vitroand their rate of digestion was examined by sodium dodecyl sulphate-polyacrylamide-gel electrophoresis. The S-rich proteins rice prolamin (10 kDa), maize zein (10 kDa) and the 3·2 kDa pumpkin (Cucurbita maximaL.) trypsin inhibitor-1 (CMTI-1) were highly resistant to rumen fluid degradation, relative to control proteins of known degradation rate (casein, bovine serum albumin (BSA) and pea (Pisum sativum) albumin-1 (PA1)). Comparison of PA1 and a recombinant N-terminal epitope-tagged PA1 indicated that addition of the epitope caused a slight increase in resistance to rumen degradation. The proteins were also incubated with a mixture of trypsin (EC3·4·21·4) and chymotrypsin (EC3·4·21.1). PA1, BSA and casein were hydrolysed less rapidly than rice prolamin, maize zein and CMTI-1. Digestion by these intestinal proteases appeared to be complete. Thus, the prolamin, zein and CMTI-1 proteins are suitable candidates for expression as foreign proteins in pasture plants to increase throughput and uptake of essential amino acids in sheep.
Databáze: OpenAIRE