This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cowman, R. A. Articles by Speck, M. L. Search for Related Content PubMed Articles by Cowman, R. A. Articles by Speck, M. L. Agricola Articles by Cowman, R. A. Articles by Speck, M. L.

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1967 July; 15(4): 851-856
Copyright © 1967 American Society for Microbiology. All Rights Reserved.

Proteinase Enzyme System of Lactic Streptococci

I. Isolation and Partial Characterization¹

Department of Food Science, North Carolina State University, Raleigh, North Carolina 27607

ABSTRACT

Proteinase activity of Streptococcus lactis cells was maximal at pH 6.0, but after storage at 3 C the minimal activity was observed at this pH. Activity lost as a result of storage could be restored by adding glutathione. Whole cells were fractionated into soluble (intracellular) and particulate fractions by sonic disruption; both fractions contained enzymatic activity. Activity of the soluble (intracellular) fraction was found to be stable to storage at 3 C, but was inhibited progressively with increasing concentrations of p-hydroxymercuribenzoate (PHMB). The enzymatic activity of this fraction was not activated by ferrous or magnesium ions or by cysteine. In contrast, activity of the particulate fraction was labile to storage at 3 C, and the reduction was comparable to that of stored cells. Furthermore, proteinase activity in the cells and the particulate fraction was not affected by addition of PHMB. The particulate fraction was activated by ferrous and magnesium ions and by cysteine. After storage, only ferrous ion and cysteine promoted reactivation; magnesium ion was totally ineffective. The enzyme(s) contained in the particulate fraction may be involved in decreased proteinase activity observed in whole cells and in the effect on growth of cells after storage.

¹ Contribution from Department of Food Science, North Carolina Agricultural Experiment Station, Raleigh. Published with approval of the Director of Research as paper no. 2316 of the Journal Series.