Proteolytic and coagulating enzymes of enterococci

Dudani, A. T.

doi:10.31274/rtd-180813-14786

Cited by 9 publications

(14 citation statements)

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“…As shown in figure 1, the optimum pH of the enzyme on casein is about 7.4. This is the same as obtained by Dudani (1950) with S.…”

Section: Resultssupporting

confidence: 81%

“…This method measures the increase in trichloracetic acid soluble tyrosine with casein as a substrate. The casein substrate was that of Dudani (1950 Crewther (1952).…”

mentioning

confidence: 99%

“…In the gelatinase assay, activity was expressed in terms of change in optical density at 540 m,u. Milk clotting was measured by the method of Dudani (1950) using White House, nonfat, dry milk solids.…”

mentioning

confidence: 99%

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A Proteolytic Enzyme of Streptococcus Zymogenes

Grutter

Zimmerman

1955

J Bacteriol

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Dudani (1950) presented some evidence which indicated that casein hydrolysis and milk clotting in Streptococc liquefacien were due to the same enzyme. It is known that the closely related species, Streptococcus zymogens, can hydrolyze casein, clot milk, and liquefy gelatin. In the present work, culture filtrates of S. zymogenes containing the enzymatic fraction responsible for the three types of activity were purified and studied. In addition, an attempt was made to determine whether these three manifestations of enzymatic activity were due to one enzyme. METHODS The organism used in this work was a nonhemolytic mutant derived from S. tymogene8 strain 26C1 by ultraviolet irrdiation (Zimmerman, 1951). All stock cultures were maintained on litmus milk. Two drops of an actively growing litmus milk culture were inoculated into a tube of litmus milk, and the tube was frozen and stored at-17 C. The incubation temperature used throughout was 37 C. A ten per cent washed cell suspension was used to inoculate a casein semisynthetic medium from which active supernates were obtained after 24 hours' incubation. The broth for inoculum had the following composition: Sheffield N-Z-Case, 1.0 g; yeast extract, 1.0 g; K2HPO4, 0.2 g; glucose, 0.1 g; and distilled water to 100 ml. The pH was adjusted to 7.0. The casein medium had the following composition: vitamin-free casein, 0.2 g; KH2PO4, 1 This report is from a dissertation submitted by Frederick H. Grutter in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of The Pennsylvania State University.

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“…As shown in figure 1, the optimum pH of the enzyme on casein is about 7.4. This is the same as obtained by Dudani (1950) with S.…”

Section: Resultssupporting

confidence: 81%

“…This method measures the increase in trichloracetic acid soluble tyrosine with casein as a substrate. The casein substrate was that of Dudani (1950 Crewther (1952).…”

mentioning

confidence: 99%

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A Proteolytic Enzyme of Streptococcus Zymogenes

Grutter

Zimmerman

1955

J Bacteriol

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“…Again the hydrolysis of PL-alanvl-PL-alstnine was the exception, not being affected by cobalt.The hydrolysis of the glycyl-peptides either was activated or only slightly 88 inhibited by cobalt at the higher pH levels. Similar results were reported by Dudani(16) who found that cobalt strongly activated the hydrolysis of glycyl-J^-leucine at pH 5. 0 by cell-free extract of S. liquefaciens.…”

supporting

confidence: 90%

“…Manganese and magnesium ions have been reported by many workers (16,44, 52 and 57) as being activators of different peptidases. In the present study these ions were found to have little effect on the enzymatic hydroly sis of peptides.…”

Section: Discussionmentioning

confidence: 92%

Proteolysis by Lactobacillus casei

Brandsaeter

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PROTEOLYTIC ENZYMES FROM PSEUDOMONAS PUTREFACIENS. II. CHARACTERISTICS OF AN ENDOCELLULAR PROTEOLYTIC ENZYME SYSTEM^a

Zant

1957

Journal of Food Science

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A previous investigation ( 7 ) showed that the cell-free growth medium of a milk culture of Ps. pzitrefaciens contained a heat-labile proteolytic enzyme system which attacked casein and lactalbumin. Subsequent experiments failed to show any peptidase activity in the extracellular preparation. The endocellular extract, however, was active against various di-and tripeptides. The literature reveals many reports on microbial peptidases ; few, however, have been studied in detail. More recently Dudani (I), Zimmerman (8), and van der Zant and Nelson (6) reported on the peptidases of some of the lactic streptococci. The optimum p H for activity usually was between p H 7.0 and 8.5. I n many instances metallic ions were necessary for optimum activity of microbial peptidases. The present study was undertaken to investigate the peptidases of Ps. putref aciens. EXPERIMENTAL METHODSThe culture Ps. putrefaciens 12 was the same organism as used in a previous study (7). The stock culture was handled as described in that paper. The culture was transfered daily for 3 transfers prior to each experiment in the culture medium employed in the trial. One percent inoculum was used with incubation at 25'' C.Preparation of cell-free extract. Ps. putrefariens 1 2 was grown in a medium of the following composition: 1 g. glucose, 5 g. yeast extract, 15 g. casamino acids, and 1 1. water. The above medium was autoclaved a t 15 Ib. steam pressure for 15 min., cooled to 25" C., adjusted to p H 7.0, and inoculated. The inoculated medium was incubated for 2 days a t 25" C. The cells were collected by centrifugation in a Sharpless super centrifuge at 30,000 r.p.m. The cells were washed twiee in ice cold phosphate buffer ( p H 7.0, M/15) and collected by centrifugation i n a refrigerated centrifuge and stored in a freezer unit. Cell-free extracts were prepared by disintegration of the cells by sonic vibration. A detailed procedure of this process was presented i n a previous publication (5). The cell-free extract was stored in a freezer unit and used within a few days.Enzyme-substrate mixture. Buffered M/30 solutions of glycyl-L-tyrosine, L-leucyl-L-tyrosine, glycylglycine, glycylglycylglycine, glycyl-DL-valine, glycyl-DL-phenylalanine, glycyl-L-tryptophan, and Y/15 solutions of DL-alanyl-DL-alanine, DL-alanylglycine, DLalanyl-DL-asparagine, and DL-leueylglycine were used as substrates. The substrates were prepared as reported in a previous publication (6). Hydrolysis of the peptides was determined by titration of the carboxyl groups with ethanolic KOH with thymolphthalein as indicator (6). Unless stated otherwise, 0.2 ml. of cell-free extract was added to 3 ml. of substrate and incubated at p H 7.0 and 35" f o r 2 hours.

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Proteolytic and coagulating enzymes of enterococci

Cited by 9 publications

References 1 publication

A Proteolytic Enzyme of Streptococcus Zymogenes

A Proteolytic Enzyme of Streptococcus Zymogenes

Proteolysis by Lactobacillus casei

PROTEOLYTIC ENZYMES FROM PSEUDOMONAS PUTREFACIENS. II. CHARACTERISTICS OF AN ENDOCELLULAR PROTEOLYTIC ENZYME SYSTEM^a

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Proteolytic and coagulating enzymes of enterococci

Cited by 9 publications

References 1 publication

A Proteolytic Enzyme of Streptococcus Zymogenes

A Proteolytic Enzyme of Streptococcus Zymogenes

Proteolysis by Lactobacillus casei

PROTEOLYTIC ENZYMES FROM PSEUDOMONAS PUTREFACIENS. II. CHARACTERISTICS OF AN ENDOCELLULAR PROTEOLYTIC ENZYME SYSTEMa

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PROTEOLYTIC ENZYMES FROM PSEUDOMONAS PUTREFACIENS. II. CHARACTERISTICS OF AN ENDOCELLULAR PROTEOLYTIC ENZYME SYSTEM^a