Submitted to: Journal of the American Society of Brewing Chemists
Publication Type: Abstract Only
Publication Acceptance Date: 2/5/1996
Publication Date: N/A
Technical Abstract: Green malt endoproteinases control the hydrolysis of storage proteins during germination and are thus of critical importance to the malting process. We have show that all four proteinase classes are present in green malt, but that the cysteine proteinases are most prevalent and that some are important for hydrolyzing storage proteins. Compounds present in barley and malt have been shown to inhibit several of the cysteine proteinases. This presentation reports the purification and characterization of a 10 kD protein from barley that specifically inhibits green malt cysteine proteinases. Amino acid composition and sequence data indicate that it is apparently identical to LTP1-PAPI, a lipid-transfer protein. The purified protein did not inhibit either papain or subtilisin but suppressed the activity of many of the cysteine endoproteolytic activities of a green malt extract after they were separated on a 2-D IEF x xPAGE gel system. The purified inhibitor also totally inhibited the activity of a purified 31 kD green malt cysteine endoproteinase that has previously been shown to rapidly hydrolyze barley storage proteins. It thus appears that LTP1-PAPI probably plays an important role in controlling the hydrolysis of proteins during malting.