Journal Article

Purification and Characterization of a New Ubiquitin C-Terminal Hydrolase (UCH-1) with Isopeptidase Activity from Chick Skeletal Muscle

Seung Kyoon Woo, Sung Hee Baek, Lee, Yung Joon Yoo, Choong Myung Cho, Man-Sik Kang and Chin Ha Chung

in The Journal of Biochemistry

Published on behalf of The Japanese Biochemical Society

Volume 121, issue 4, pages 684-689
Published in print April 1997 | ISSN: 0021-924X
Published online April 1997 | e-ISSN: 1756-2651 | DOI: http://dx.doi.org/10.1093/oxfordjournals.jbchem.a021640
Purification and Characterization of a New Ubiquitin C-Terminal Hydrolase (UCH-1) with Isopeptidase Activity from Chick Skeletal Muscle

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We have previously shown that chick muscle extracts contain at least 10 different ubiquitin C-terminal hydrolases (UCHs). In the present studies, one of the enzymes, called UCH-1 was partially purified by conventional chromatographic procedures using 125I-labeled ubiquitin-αNH-MHISPPEPESEEEEEHYC as a substrate. The purified enzyme behaved as a 36-kDa protein under both denaturing and nondenaturing conditions, suggesting that it consisted of a single polypeptide chain. It was maximally active at pHs between 8 and 9, but showed little or no activity at pH below 6 and above 11. Like other UCHs, its activity was strongly inhibited by sulfhydryl blocking reagents, such as iodoacetamide, and by ubiquitin-aldehyde. In addition to Ub-PESTc, UCH-1 hydrolyzed ubiquitin-αNH-protein extensions, including ubiquitin-αNH-carboxyl extension protein of 80 amino acids, ubiquitin-αNH-dihydrofolate reductase, and poly-His-tagged di-ubiquitin. This enzyme was also capable of generating free ubiquitin from mono-ubiquitin-εNH-protein conjugates and from branched poly-ubiquitin chains that are ligated toproteins through εNH-isopeptide bonds. These results suggest that UCH-1 may play an important role in the generation of free ubiquitin from ubiquitin-ribosomal protein fusions and linear polyubiquitin, as well as in recycling of Ub molecules after degradation of poly-ubiquitinated protein conjugates by the 26S proteasome.

Keywords: isopeptidase; ubiquitin C-terminal hydrolase; ubiquitin specific protease

Journal Article.  0 words. 

Subjects: Biochemistry

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