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Updated: Jul 1, 2026

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins
Published on: October 4, 2017
Modulation of cystathionine beta-synthase activity by the Arg-51 and Arg-224 mutations
Shin-Ichi Ozaki1, Atsushi Inada, Kazuya Sada
1Department of Biological Sciences, Yamaguchi University, Yamaguchi, Japan. ozakis@yamaguchi-u.ac.jp
Abstract:
Human cystathionine beta-synthase (CBS) catalyzes a pyridoxal 5'-phosphate (PLP) dependent beta-replacement reaction to synthesize cystathionine from serine and homocysteine. The enzyme is unique in bearing not only a catalytically important PLP but also heme. In order to study a regulatory process mediated by heme, we performed mutagenesis of Arg-51 and Arg-224, which have hydrogen-bonding interactions with propionate side chains of the prosthetic group. It was found that the arginine mutations decrease CBS activity by approximately 50%. The results indicate that structural changes in the heme vicinity are transmitted to PLP existing 20 A away from heme. A possible explanation of our results is discussed on the basis of CBS structure.
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