Mutagenesis Studies of Human Cystathionine β-Synthase: Residues Important for Heme Binding and Substrate Interactions

Human cystathionine β-synthase (CBS) is a pyridoxal 5'-phosphate (PLP) dependent hemoprotein, which catalyzes the condensation of serine and homocysteine. Our mutagenesis studies suggest that Arg-266 is important to sense structural changes in heme-binding site, and that Gln-222 as well as Tyr-223 are involved in interactions with substrates.