title: Interactions of malt and barley (Hordeum vulgare L.) endoproteinases with their endogenous inhibitors.
abstract: For producing worts that are optimal for beer production, some, but not all, of the barley proteins must be degraded during malting and mashing. This protein hydrolysis is controlled by endoproteinases, and, in turn, is partially regulated by the presence of low-molecular-weight (LMW) proteinaceous inhibitors. This paper reports studies of the interactions between the proteinases and inhibitors and an "affinity" method for concentrating the inhibitors. The malt inhibitors (I) and proteinases (E) quickly formed strong (E-I) complexes when dissolved together, and all of the I was complexed. Heating at 100 degrees C, but not 70 degrees C, dissociated the complex, even though the enzyme activities were destroyed at 70 degrees C. The released I readily recomplexed with fresh E. Barley, however, contained insufficient E to complex all of its I complement. The E-I complex was treated with salts, detergents, and reducing agents to release active E molecules, but none disrupted the complex. By removing the LMW proteins from a malt E-I extract and dissociating the complex by heating, the concentration of I molecules was greatly increased. This "affinity" method can thus be used to concentrate the I molecules for further purification.
authors.affiliation: Cereal Crops Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Madison, Wisconsin 53705, USA. BLJONES@facstaff.wisc.edu
authors.forename: B L
authors.initials: BL
authors.lastname: Jones
mesh_terms: D001515:Beer; D002850:Chromatography, Gel; D002523:Edible Grain / Q000201:enzymology*; D010450:Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D001467:Hordeum / Q000201:enzymology*; D006868:Hydrolysis; D010940:Plant Proteins / Q000378:metabolism; D011480:Protease Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D011485:Protein Binding
chemical_list: D010940:Plant Proteins; D011480:Protease Inhibitors; D010450:Endopeptidases