|
type |
Journal Article |
authors |
Gosling, J. P.; Fottrell, P. F. |
title |
Purification and characterisation of D-amino acid aminotransferase from Rhizobium japonicum |
journal |
Biochim Biophys Acta |
Activity |
2.6.1.21 |
ui |
78080904 |
year |
(1978) |
volume |
522 |
number |
1 |
pages |
84-9. |
| |
keywords |
Alanine Transaminase/metabolism |
abstract |
Rhizobium japonicum has D-amino acid aminotransferase and alanine racemase activities. The D-amino-acid aminotransferase has been partially purified and characterized. This enzyme has a broad specificity and is very active with D-alpha-aminobutyrate and D- aspartate as well as D-alanine and D-glutamate. The stereospecificity of the enzyme for D-amino acids was apparently absolute with respect to product inhibition, pyridoxamine formation as well as catalytic activity. The apparent molecular weight was 58,000 and the pH optimum was 7.8-7.9. The equilibrium constant in the direction of D-glutamate formation was 1.9. Initial-velocity kinetic studies indicate the enzyme acts by a ping-pong mechanism. The dissociation constant for pyridoxal phosphate and the Michaelis constants (+/- standard errors) for D- alanine and 2-oxoglutarate were determined to be 0.51 +/- 0.06 micrometer, and 2.13 +/- 0.18 and 0.058 +/- 0.005 mM respectively. The enzyme is moderately inhibited (30%) by 4 mM p-chloromercuribenzoate. |
last changed |
2002/11/04 17:41 |
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