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Enzyme Systems in Tetrahymena pyriformis S. VI. Urea Formation and Breakdown *
Author(s) -
SEAMAN GERALD R.
Publication year - 1954
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1954.tb00818.x
Subject(s) - tetrahymena pyriformis , arginase , citrulline , urease , tetrahymena , biochemistry , urea , enzyme , ornithine , malachite green , chemistry , ciliate , biology , arginine , organic chemistry , ecology , amino acid , adsorption
Cell‐free extracts of Tetrahymena pyriformis S synthesize citrulline from ornithine, and arginine from citrulline. The extracts also show arginase activity. Urease activity at various pH values has maxima at both pH 5.6 and 7.4. This points to two distinct enzymes. The presence of urea in ciliate cultures during early stages of growth, and its absence during the stationary phase of cultures, correlate with the shift in pH of the culture media and with the activity of the “alkaline” urease at various pH values.