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Appl Environ Microbiol. 1975 November; 30(5): 738-745
Copyright © 1975 American Society for Microbiology. All Rights Reserved.

Purification and Properties of Intracellular Proteinase from Streptococcus cremoris

Department of Food Science and Technology, Nagoya University, Chikusa, Nagoya 464, Japan

ABSTRACT

Proteolytic activity in the extract from the cells of Streptococcus cremoris increased in the presence of casein, lactose, glucose, and CaCl₂ in the media but was negligibly detectable in the extract of the cells harvested from the culture containing succinate or citrate. The intracellular proteinase from S. cremoris harvested from tomato medium was purified 150-fold in this experiment. The enzyme had a molecular weight of 140,000, optimum pH at 6.5 to 7.0, and maximum activity at 30 C. The proteinase was activated by Ca²⁺ and inhibited by Zn²⁺, Cu²⁺, Hg²⁺, Fe²⁺, ethylenediaminetetraacetate, and sodium lauryl sulfate. The K_m value of the enzyme towards each casein fraction was almost the same, and the V_max of the enzyme towards _s-casein was smaller than those towards the other casein fractions.