PMID: 2501302Jul 25, 1989Paper

The non-flavin redox center of the streptococcal NADH peroxidase. I. Thiol reactivity and redox behavior in the presence of urea.

The Journal of Biological Chemistry
L B Poole, A Claiborne

Abstract

Unlike the 2-electron-reduced (EH2) forms of the flavoprotein disulfide reductases and mercuric reductase, the native EH2 form of the streptococcal NADH peroxidase is quite refractile toward chemical modification with thiol-specific reagents. In the presence of 1.3 M urea, however, the single thiol of the reduced enzyme reacts with phenylmercuric acetate with a t1/2 of 3 min. This modification abolishes the charge-transfer absorbance band at 540 nm and inactivates the enzyme; the latter effect is shown to be reversed with dithiothreitol. Alkylation of the streptococcal peroxidase with iodo[1-14C]acetamide under reducing conditions in the presence of 8 M guanidine hydrochloride allows the isolation of a single labeled tryptic peptide with the sequence: Gly-Asp-Phe-Ile-Ser-Phe-Leu-Ser-C*ys-Gly-Met-Gln-Leu-Tyr-Leu- Glu-Gly-Lys. This sequence is identical to that previously reported (Poole, L. B., and Claiborne, A. (1988) Biochem. Biophys. Res. Commun. 153, 261-266) for the cysteinyl peptide isolated from the NADH peroxidase labeled metabolically with [35S]cysteine. Careful examination of the physical properties of the streptococcal peroxidase in the presence of 1.3 M urea shows that, while catalytic activity and native structural ...Continue Reading

Related Concepts

Related Feeds

ASBMB Publications

The American Society for Biochemistry and Molecular Biology (ASBMB) includes the Journal of Biological Chemistry, Molecular & Cellular Proteomics, and the Journal of Lipid Research. Discover the latest research from ASBMB here.