| Literature DB >> 8175682 |
K Hoffmann1, E Schneider-Scherzer, H Kleinkauf, R Zocher.
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.Entities:
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Year: 1994 PMID： 8175682
Source DB: PubMed Journal: J Biol Chem ISSN： 0021-9258 Impact factor: 5.157