Purification and partial characterization of 3-hydroxyisobutyryl-coenzyme A hydrolase of rat liver

Yoshiharu Shimomura, Taro Murakami, Noriaki Fujitsuka, Naoya Nakai, Yuzo Sato, Satoru Sugiyama, Noriko Shimomura, Jamie Irwin, John W. Hawes, Robert A. Harris

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Abstract

An unusual feature of valine catabolism is a reaction in which an intermediate of its catabolic pathway, (S)-3-hydroxyisobutyryl-CoA, is hydrolyzed to give the free acid and CoA-SH. The enzyme responsible for this reaction, 3-hydroxyisobutyryl-CoA hydrolase (EC 3.1.2.4), was purified 7200- fold from rat liver in this study. The purified enzyme consists of a single polypeptide with an M(r) of 36,000 in the native and denatured forms. The hydrolase is highly specific for (S)-3-hydroxyisobutyryl-CoA and 3- hydroxypropionyl-CoA (K(m), 6 and 25 μM, respectively) with optimal activity around pH 8. The turnover rate of the enzyme for (S)-3-hydroxyisobutyryl-CoA is 270 s-1, which is high relative to other enzymes of the valine pathway. Likewise, activity of the enzyme expressed on a wet weight basis is also very high in the major tissues of the rat. These findings suggest that rapid destruction of (S)-3-hydroxyisobutyryl-CoA produced during valine catabolism is physiologically important. We propose that the need for a mechanism to protect cells against the toxic effects of methacrylyl-CoA, which is maintained in equilibrium with (S)-3-hydroxyisobutyryl-CoA by crotonase, explains why valine catabolism involves this enzyme and why its tissue activity is so high.

Original languageEnglish (US)
Pages (from-to)14248-14253
Number of pages6
JournalJournal of Biological Chemistry
Volume269
Issue number19
StatePublished - May 13 1994

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Shimomura, Y., Murakami, T., Fujitsuka, N., Nakai, N., Sato, Y., Sugiyama, S., Shimomura, N., Irwin, J., Hawes, J. W., & Harris, R. A. (1994). Purification and partial characterization of 3-hydroxyisobutyryl-coenzyme A hydrolase of rat liver. Journal of Biological Chemistry, 269(19), 14248-14253.