Publications

• Selenocysteine lyase, a novel enzyme that specifically acts on selenocysteine. Mammalian distribution and purification and properties of pig liver enzyme.

  Esaki N., Nakamura T., Tanaka H., Soda K.

  We have found a novel enzyme that exclusively decomposes L-selenocysteine into L-alanine and H2Se in various mammalian tissues, and have named it selenocysteine lyase. The enzyme from pig liver has been purified to homogeneity. It has a molecular weight of approximately 85,000, and contains pyrido ... >> More

  We have found a novel enzyme that exclusively decomposes L-selenocysteine into L-alanine and H2Se in various mammalian tissues, and have named it selenocysteine lyase. The enzyme from pig liver has been purified to homogeneity. It has a molecular weight of approximately 85,000, and contains pyridoxal 5'-phosphate as a coenzyme. Its maximum reactivity is at about pH 9.0. Balance studies showed that 1 mol of selenocysteine is converted to equimolar amounts of alanine and H2Se. The following amino acids are insert: L-cysteine, L-serine, L-cysteine sulfinate, selenocysteamine, Se-ethyl-DL-selenocysteine, and L-selenohomocysteine. L-Cysteine (Ki, 1.0 mM) competes with L-selenocysteine (Km, 0.83 mM) to inhibit the enzyme reaction. The enzyme is the first proven enzyme that specifically acts on selenium compounds. << Less

  J Biol Chem 257:4386-4391(1982) [PubMed] [EuropePMC]

• Cysteine sulfinate desulfinase, a NIFS-like protein of Escherichia coli with selenocysteine lyase and cysteine desulfurase activities. Gene cloning, purification, and characterization of a novel pyridoxal enzyme.

  Mihara H., Kurihara T., Yoshimura T., Soda K., Esaki N.

  Selenocysteine lyase (EC 4.4.1.16) exclusively decomposes selenocysteine to alanine and elemental selenium, whereas cysteine desulfurase (NIFS protein) of Azotobacter vinelandii acts indiscriminately on both cysteine and selenocysteine to produce elemental sulfur and selenium respectively, and ala ... >> More

  Selenocysteine lyase (EC 4.4.1.16) exclusively decomposes selenocysteine to alanine and elemental selenium, whereas cysteine desulfurase (NIFS protein) of Azotobacter vinelandii acts indiscriminately on both cysteine and selenocysteine to produce elemental sulfur and selenium respectively, and alanine. These proteins exhibit some sequence homology. The Escherichia coli genome contains three genes with sequence homology to nifS. We have cloned the gene mapped at 63.4 min in the chromosome and have expressed, purified to homogeneity, and characterized the gene product. The enzyme comprises two identical subunits with 401 amino acid residues (Mr 43,238) and contains pyridoxal 5'-phosphate as a coenzyme. The enzyme catalyzes the removal of elemental sulfur and selenium atoms from L-cysteine, L-cystine, L-selenocysteine, and L-selenocystine to produce L-alanine. Because L-cysteine sulfinic acid was desulfinated to form L-alanine as the preferred substrate, we have named this new enzyme cysteine sulfinate desulfinase. Mutant enzymes having alanine substituted for each of the four cysteinyl residues (Cys-100, Cys-176, Cys-323, and Cys-358) were all active. Cys-358 corresponds to Cys-325 of A. vinelandii NIFS, which is conserved among all NIFS-like proteins and catalytically essential (Zheng, L., White, R. H., Cash, V. L., and Dean, D. R. (1994) Biochemistry 33, 4714-4720), is not required for cysteine sulfinate desulfinase. Thus, the enzyme is distinct from A. vinelandii NIFS in this respect. << Less

  J. Biol. Chem. 272:22417-22424(1997) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Reaction mechanism and molecular basis for selenium/sulfur discrimination of selenocysteine lyase.

  Omi R., Kurokawa S., Mihara H., Hayashi H., Goto M., Miyahara I., Kurihara T., Hirotsu K., Esaki N.

  Selenocysteine lyase (SCL) catalyzes the pyridoxal 5'-phosphate-dependent removal of selenium from l-selenocysteine to yield l-alanine. The enzyme is proposed to function in the recycling of the micronutrient selenium from degraded selenoproteins containing selenocysteine residue as an essential c ... >> More

  Selenocysteine lyase (SCL) catalyzes the pyridoxal 5'-phosphate-dependent removal of selenium from l-selenocysteine to yield l-alanine. The enzyme is proposed to function in the recycling of the micronutrient selenium from degraded selenoproteins containing selenocysteine residue as an essential component. The enzyme exhibits strict substrate specificity toward l-selenocysteine and no activity to its cognate l-cysteine. However, it remains unclear how the enzyme distinguishes between selenocysteine and cysteine. Here, we present mechanistic studies of selenocysteine lyase from rat. ESI-MS analysis of wild-type and C375A mutant SCL revealed that the catalytic reaction proceeds via the formation of an enzyme-bound selenopersulfide intermediate on the catalytically essential Cys-375 residue. UV-visible spectrum analysis and the crystal structure of SCL complexed with l-cysteine demonstrated that the enzyme reversibly forms a nonproductive adduct with l-cysteine. Cys-375 on the flexible loop directed l-selenocysteine, but not l-cysteine, to the correct position and orientation in the active site to initiate the catalytic reaction. These findings provide, for the first time, the basis for understanding how trace amounts of a selenium-containing substrate is distinguished from excessive amounts of its cognate sulfur-containing compound in a biological system. << Less

  J. Biol. Chem. 285:12133-12139(2010) [PubMed] [EuropePMC]