| |
[摘要]：L-DOPA-2,3-dioxygenase from Streptomyces lincolnensis is a single-domain type I extradiol dioxygenase of the vicinal oxygen chelate superfamily and catalyzes the second step in the metabolism of tyrosine to the propylhygric acid moiety of the antibiotic, lincomycin. S. lincolnensis L-DOPA-2,3-dioxygenase was over-expressed, purified and reconstituted with Fe(II). The activity Of L-DOPA-2,3-dioxygenase was kinetically characterized with L-DOPA (K-M = 38 mu M, k(cat) = 4.2 min(-1)) and additional catecholic substrates including dopamine, 3,4-dihydroxyliydrocinnamic acid, catechol and D-DOPA. 3,4-Dihydroxyphenylacetic acid was characterized as a competitive inhibitor of the enzyme (Ki = 2.2 mM). Site-directed mutagenesis and its effects on enzymatic activity were used to identify His14 and His70 as iron ligands. (C) 2008 Elsevier Inc. All rights reserved. |
|
