ARS | Publication request: BARLEY LTPI (PAPI) AND LTP2 ARE INHIBITORS OF GREEN MALT CYSTEINE ENDOPROTEINASES

Submitted to: Journal of American Society of Brewing Chemists
Publication Type: Other
Publication Acceptance Date: September 12, 1995
Publication Date: N/A

Interpretive Summary: Small proteins present in barley and malt, called proteinase inhibitors, can affect how well the malt works for brewing. We have, for the first time, prepared pure proteinase inhibitors from barley seeds and have determined their structures. It turns out that these inhibitors had been studied previously, under the names lipid transfer proteins 1 and 2. Now that it is known what these two compounds are, we will be able to develop barleys having altered amounts of them. Hopefully, these new barleys will make better malts than those now available.

Technical Abstract: Barley and malt endoproteinases determine how proteins are hydrolyzed during malting. Proteins that inhibit their activities (proteinase inhibitors) will have a great influence on their activities, and thus on protein hydrolysis. This, in turn, will affect the brewing quality of a malt. We have purified and characterized two proteinase inhibitors from barley seeds and have determined that they are the same proteins that were previously thought to be lipid transfer proteins 1 and 2 (LTP1 and LTP2). LTP 1 has also been known as the probable amylase/protease inhibitor (PAPI) of barley. Knowing the identity of these inhibitors makes it possible to manipulate them to develop barleys with improved malting quality.