A STUDY OF TWO YEAST PROTEINASES
1956; Elsevier BV; Volume: 221; Issue: 2 Linguagem: Inglês
10.1016/s0021-9258(18)65206-8
ISSN1083-351X
Autores Tópico(s)Enzyme Production and Characterization
ResumoAutolysis is a procedure frequently employed in the isolation of materials from yeast.Although the intracellular yeast proteinases play an important r81e in autolysis, these enzymes have not been characterized by using up to date methods of analysis, and the existing literature concerning yeast proteinases presents conflicting results.In 1917, Dernby (1) reported that yeast contains two proteinases, a 'Lpepsin" and a "tryptase."The presence of two proteinases was indicated mainly by the fact that a yeast autolysate showed two pH optima for gelatin liquefaction; namely, at pH 4.5 and pH 7.0.In 1926-28, Grassmann, Willstltter, and coworkers published a series of papers on the proteolytic activity of yeast (2-4).These authors concluded that there is only one proteinase in yeast.This enzyme was reputed to be of the papain type with an optimal pH of 5.0 as measured by an alcoholic KOH titration of gelatin hydrolysis (4).However, in 1936, Hecht and Civin (5) claimed that yeast contains a "pepsin" which displays optimal activity at pH 1.8.In the present paper, the separation and partial characterization of two individual yeast proteinases are described.One has an optimal pH of about 3.7 and is rapidly denatured by urea.The other has optimal activity at pH 6.2 and may be activated by concentrated urea solutions.
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