Cysteine synthase catalyzes the formation of cysteine from O-acetylserine, and is the key enzyme for de novo cysteine biosynthesis in Schizosaccharomyces pombe. An examination of the S. pombe database revealed that two gene products are predicted to encode proteins homologous to eukaryotic cysteine synthases. Disruption of one of these candidates, cys1a+ (SPBC36.04), caused an obvious cysteine ...

Lipoxygenases have been proposed to be a possible factor that is responsible for the pathology of certain diseases, including ischaemic injury. In the peroxidation process of linoleic acid by lipoxygenase, the E,Z-linoleate allyl radical-lipoxygenase complex seems to be generated as an intermediate. In the present study, we evaluated whether E,Z-linoleate allyl radicals on the enzyme are scaven...

Protein S-sulfhydration is a newly discovered post-translational modification of specific cysteine residue(s) in target proteins, which is involved in a broad range of cellular functions and metabolic pathways. By changing local conformation and the final activity of target proteins, S-sulfhydration is believed to mediate most cellular responses initiated by H₂S, a novel gasotransmitter. In com...

The specificity of substrates for measuring cystyl-amino peptidase activity in pregnant serum in the assessment of placental function was studied, using £-cystine-di-j3-naphthylamide, L-cystine-bis-/?-nitroanilide,/,-cysteine-j3naphthylamide, and S-benzyl-i-cysteine-p-nitroanilide. The enzyme activity with S-benzyl-Z,-cysteine-/?-nitroanilide increased more rapidly and markedly than with other ...

We have investigated the mechanism of action of Aquifex aeolicus IspH [E-4-hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP) reductase], together with its inhibition, using a combination of site-directed mutagenesis (K ( M ),V (max)), EPR and (1)H, (2)H, (13)C, (31)P, and (57)Fe-electron-nuclear double resonance (ENDOR) spectroscopy. On addition of HMBPP to an (unreactive) E126A IspH mutant, a re...

S-Nitrosothiols or thionitrites with the general formula RSNO are formally composed of the nitrosyl cation (NO+) and a thiolate (RS-), the base of the corresponding acids RSH. The smallest S-nitrosothiol is HSNO and derives from hydrogen sulfide (HSH, H2S). The most common physiological S-nitrosothiols are derived from the amino acid L-cysteine (CysSH). Thus, the simplest S-nitrosothiol is S-ni...

Cysteine conjugate beta-lyase activity from rat kidney cortex was found in the cystosolic and mitochondrial fractions. With 2 mM S-(2-benzothiazolyl)-L-cysteine as the substrate, approximately two-thirds of the total beta-lyase activity was present in the cytosolic fraction. The kinetics of beta-lyase activity with three cysteine S-conjugates were different in the cytosolic and mitochondrial fr...