|
type |
Journal Article |
authors |
Hoffmann, K.; Schneider-Scherzer, E.; Kleinkauf, H.; Zocher, R. |
title |
Purification and characterization of eucaryotic alanine racemase acting as key enzyme in cyclosporin biosynthesis |
journal |
J Biol Chem |
Activity |
5.1.1.1 |
Family |
5.1.1.1.b |
ui |
Pcearae |
year |
(1994) |
volume |
269 |
number |
17 |
pages |
12710-4 |
| |
keywords |
Alanine Racemase/*isolation & purification/metabolism |
abstract |
A specific alanine racemase, which is a key enzyme in the biosynthesis of the undecapeptide cyclosporin A, was purified to electrophoretic homogeneity from the fungus Tolypocladium niveum. This is the first enzyme of this kind isolated from a eucaryotic organism. The enzyme catalyzes the reversible racemization of alanine and requires pyridoxal phosphate as the exclusive cofactor. Km values for L- and D-alanine were found to be 38 and 2 mM, respectively. Maximal reaction velocity was observed at 42 degrees C and pH 8.8 for the L to D direction. Molecular mass determinations of the denatured enzyme by SDS-polyacrylamide gel electrophoresis gave a value of 37 kDa, whereas gel filtration calibration studies yielded a value between 120 and 150 kDa, indicating an oligomeric native structure. |
last changed |
2008/05/15 18:54 |
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