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Occurrence of a catabolic L-serine (L-threonine) deaminase in Saccharomyces cerevisiae.
- Source :
-
European journal of biochemistry [Eur J Biochem] 1982 Apr; Vol. 123 (3), pp. 571-6. - Publication Year :
- 1982
-
Abstract
- Saccharomyces cerevisiae mutants lacking the anabolic L-threonine deaminase, the ilv1- mutants, have been found to exhibit a normal ability to grow, without auxotrophy towards isoleucine, on L-threonine of L-serine as only nitrogen nutrient. Starting from a strain carrying a ilv1- mutation, a new mutation affecting the ability to utilize L-threonine as nitrogen source was selected. This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase. This enzyme which, unlike the anabolic threonine deaminase, is more active towards serine than towards threonine, differs from the latter enzyme by a number of biochemical and regulatory properties. Whereas the anabolic enzyme is an allosteric enzyme sensitive to feedback inhibition by isoleucine, the catabolic enzyme exhibits Michaelian kinetics: no control of its activity has been detected. Its synthesis is induced by L-serine and L-threonine. These two enzymes, which thus can be easily differentiated by means of their regulations, display a limited ability to compensate for one another's absence and appear to play clearly distinct roles under normal physiological conditions.
Details
- Language :
- English
- ISSN :
- 0014-2956
- Volume :
- 123
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- European journal of biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 7042346
- Full Text :
- https://doi.org/10.1111/j.1432-1033.1982.tb06570.x