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 Sardinas, J. L. Search for Related Content PubMed Articles by Sardinas, J. L. Agricola Articles by Sardinas, J. L.

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1968 February; 16(2): 248-255
Copyright © 1968 American Society for Microbiology. All Rights Reserved.

Rennin Enzyme of Endothia parasitica

Medicinal Research Laboratories, Natural Products Division, Charles Pfizer and Co., Inc., Groton, Connecticut 06340

ABSTRACT

A microbiological screening program was instituted to search for an animal rennet substitute. Among 381 bacteria and 540 fungi tested, only one organism, Endothia parasitica, yielded a suitable enzyme substitute. The fungal rennin enzyme was crystallized and some of its properties were studied. It was found to be water-soluble, nondialyzable, precipitable with (NH₄)₂SO₄ and organic solvents (e.g., acetone and isopropanol), and destroyed by heating for 5 min at 60 C. It was determined to be most stable in water at pH 4.5 and to have an isoelectric point of pH 5.5. On acid hydrolysis, it yielded: alanine, ammonia, arginine, aspartic acid, cysteic acid, cystine, glutamic acid, glycine, histidine, isoleucine, leucine, phenylalanine, proline, serine, threonine, tyrosine, and valine. No tryptophan was detected after alkaline hydrolysis. Its molecular weight was estimated to be in the range of 34,000 to 39,000. The milk-clotting activities of the fungal and animal rennins proved to be essentially identical in milk containing various concentrations of CaCl₂. Both rennins manifested comparable clotting activities in milk at pH 6.0 to 7.0.