| Autor: |
Stone EM; Department of Chemical Engineering, University of Texas, Austin, 78712, USA., Glazer ES, Chantranupong L, Cherukuri P, Breece RM, Tierney DL, Curley SA, Iverson BL, Georgiou G |
| Jazyk: |
angličtina |
| Zdroj: |
ACS chemical biology [ACS Chem Biol] 2010 Mar 19; Vol. 5 (3), pp. 333-42. |
| DOI: |
10.1021/cb900267j |
| Abstrakt: |
Replacing the two Mn(2+) ions normally present in human Arginase I with Co(2+) resulted in a significantly lowered K(M) value without a concomitant reduction in k(cat). In addition, the pH dependence of the reaction was shifted from a pK(a) of 8.5 to a pK(a) of 7.5. The combination of these effects led to a 10-fold increase in overall catalytic activity (k(cat)/K(M)) at pH 7.4, close to the pH of human serum. Just as important for therapeutic applications, Co(2+) substitution lead to significantly increased serum stability of the enzyme. Our data can be explained by direct coordination of l-Arg to one of the Co(2+) ions during reaction, consistent with previously reported model studies. In vitro cytotoxicity experiments verified that the Co(2+)-substituted human Arg I displays an approximately 12- to 15-fold lower IC(50) value for the killing of human hepatocellular carcinoma and melanoma cell lines and thus constitutes a promising new candidate for the treatment of l-Arg auxotrophic tumors. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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