Germination proteases

Starch derived from maize, potatoes, barley, cassava or other somces must be pretreated with hydrolytic enzymes (amylases, amyloglucosidase, proteases), which carry out liquefaction, saccharification and protein hydrolysis, respectively, before it can be fermented by yeasts and other microorganisms into potable or non-potable alcohol. Enzymes can be added in the form of malt (germinated barley) or koji (germinated rice), but this is expensive. Therefore, industrial enzymes have nearly totally replaced malt and koji as enzyme sources, thereby not only improving the economics but also the predictability of the process. 

In limited proteolysis, proteases such as pronase E hydrolyzed the 7S subunits of soy proteins more than the IIS subunits, resulting in enhanced protein solubility. Deamidation with relatively insignificant peptide bond hydrolysis that occurred during the germination of soybeans imparted to the storage protein improved solubility and emulsifying activity. On the other hand, the incorporation of phosphorus in soy proteins by the protein kinase cAMPdPK was too low to effect significant... 

Rapid degradation of proteins is often induced at certain stages of differentiation. For example, sporeforming bacteria contain a protease that becomes activated upon germination of the spore.131 Within minutes this enzyme digests stored proteins to provide amino acids for the synthesis of new proteins during growth. 

Vidyavathi, U., Shivaraj, B., and Pattabiraman, T. N. (1983). Proteases in germinating finger millet (Eleusine coracana) seeds. ]. Biosci. 5, 219-224. 

Qazi, S. S., and Khachatourians, G. G. (2008). Addition of exogenous carbon and nitrogen sources to aphid exuviae modulates synthesis of proteases and chitinase by germinating conidia of Beauveria bassiana. Archives of Microbiology, 189, 589-96. 

Dunaevsky, Y.E., Sarbakanova, S.T., Belozersky, M.A. 1989. Wheat seed carboxypeptidase and joint action on gliadin of proteases from dry and germinating-seeds. J Exp Bot 40 1323-1329. 

A second widely-studied role of GA is the induction of enzymes during the germination of certain grass seeds [74]. For example, GA induces the aleurone cells of barley seeds to produce a-amylase, which then is transported to the endosperm where it assists in the production of soluble sugars from starch. Other enzymes, such as several proteases, are also induced by GA in these cells. 

Several different forms of protease inhibitors have been isolated from soybeans, and several genetic variants of the two major soy protease Inhibitors (Kunltz trypsin Inhibitor and Bowman-Blrk inhibitor) have been identified. A new form of TI Immunochemlcally identical to the Kunitz TI appeared during germination of six populations of soybeans. These studies have been reviewed elsewhere (AO). In spite of differences in level of protease activity and the presence of protease inhibitor variants, heat treatment was effective in obtaining maximum PER and in eliminating pancreatic hypertrophy in soybean meals prepared from several varieties and strains of mature soybeans (Al). 

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