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GrainGenes Reference Report: JCS-30-237

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Reference	JCS-30-237
Title	LTP is not a cysteine endoprotease inhibitor in barley grains
Journal	Journal of Cereal Science
Year	1999
Volume	30
Pages	237-244
Author	Davy A Svendsen I Bech L Simpson DJ Cameron-Mills V
Abstract	Several different protease inhibitors have been identified in the mature barley grain, which are proposed to play a defensive role against potential barley pathogens. Cysteine protease inhibitors have been detected in mature grain and in the early stages of germination. The nature of these inhibitors has recently been investigated, and barley lipid transfer protein (LTP1) has been identified as an effective inhibitor of both cysteine and serine endoprotease activity expressed in germinating grain. We show that barley LTP1, in its native state, is not a cysteine protease inhibitor, but in a denatured state becomes a preferred substrate for the barley endoprotease EP-B and, as such, behaves as a competitive inhibitor for poorer substrates of EP-B. The presence of significant amounts of LTP1 in barley malt beer suggests that this very compact protein is highly resistant to proteolytic attack during malting and mashing and its denaturation during wort boiling coincides with inactivation of the malt endoproteases. Analysis of the cleavage products of denatured LTP1, generated by EP-B, provides further evidence for the cleavage site specificity of this barley cysteine endoprotease, where a hydrophobic residue in the P2 position is strongly preferred
Keyword	[ Hide all but 1 of 29 ] amino acid sequence attack barley beer binding proteins boiling cysteine cysteine protease cysteine proteinases enzyme activity foams germination hordein inactivation inhibitor its kernels malt malting malting barley p2 pathogen proteinase proteinase inhibitors proteolysis residue resistant serine endoprotease specificity

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