6199-20-8

Upstream product

• 56-89-3 L-cystine 
• 52-90-4 L-Cysteine 
• 134861-13-5 N-(benzoylsulfide)benzamide 

Relevant academic research and scientific papers

Iterative synthetic strategies and gene deletant experiments enable the first identification of polysulfides in: Saccharomyces cerevisiae

New evidence on the role of H2S as a gasotransmitter suggests that the true signalling effectors are polysulfides. Both oxidized polysulfides and hydropolysulfides were synthesized and their presence in S. cerevisiae was observed for the first time. A single gene-deletant approach allowed observation of the modulation of polysulfide species and levels.

C-S bond cleavage by a polyketide synthase domain

Leinamycin (LNM) is a sulfur-containing antitumor antibiotic featuring an unusual 1,3-dioxo-1,2-dithiolane moiety that is spiro-fused to a thiazole-containing 18-membered lactam ring. The 1,3-dioxo-1,2- dithiolane moiety is essential for LNM's antitumor activity, by virtue of its ability to generate an episulfonium ion intermediate capable of alkylating DNA. We have previously cloned and sequenced the lnm gene cluster from Streptomyces atroolivaceus S-140. In vivo and in vitro characterizations of the LNM biosynthetic machinery have since established that: (i) the 18-membered macrolactam backbone is synthesized by LnmP, LnmQ, LnmJ, LnmI, and LnmG, (ii) the alkyl branch at C-3 of LNM is installed by LnmK, LnmL, LnmM, and LnmF, and (iii) leinamycin E1 (LNM E1), bearing a thiol moiety at C-3, is the nascent product of the LNM hybrid nonribosomal peptide synthetase (NRPS)-acyltransferase (AT)-less type I polyketide synthase (PKS). Sulfur incorporation at C-3 of LNM E1, however, has not been addressed. Here we report that: (i) the bioinformatics analysis reveals a pyridoxal phosphate (PLP)-dependent domain, we termed cysteine lyase (SH) domain (LnmJ-SH), within PKS module-8 of LnmJ; (ii) the LnmJ-SH domain catalyzes C-S bond cleavage by using L-cysteine and L-cysteine S-modified analogs as substrates through a PLP-dependent β-elimination reaction, establishing L-cysteine as the origin of sulfur at C-3 of LNM; and (iii) the LnmJ-SH domain, sharing no sequence homology with any other enzymes catalyzing C-S bond cleavage, represents a new family of PKS domains that expands the chemistry and enzymology of PKSs and might be exploited to incorporate sulfur into polyketide natural products by PKS engineering.

Cysteine-activated hydrogen sulfide (H2S) donors

H2S, the newly discovered gasotransmitter, plays important roles in biological systems. However, the research on H2S has been hindered by the lack of controllable H2S donors that could mimic the slow and continuous H2S generation process in vivo. Herein we report a series of cysteine-activated H2S donors. Structural modifications of these molecules can regulate the rates of H2S generation. These compounds can be useful tools in H2S research.

Purification and Characterization of Cystine Lyase a from Broccoli Inflorescence

One of the three isoforms of an enzyme degrading L-cystine was purified to homogeneity from broccoli (Brassica oleracea var. italica) inflorescences, with use of a sensitive assay based on derivatization of a reaction product with monobromobimane. The reaction product with a thiol group was found to be thiocysteine from results of liquid chromatography-mass spectrometry and high-resolution mass spectrometry. Pyruvate was also a reaction product, formed in equimolar amounts. The purified enzyme catalyzed β-elimination of L-cystine to yield thiocysteine, pyruvate and possibly ammonia, so it was cystine lyase a. L-Cystine but not D-cystine was a substrate of the enzyme. S-Methyl L-cysteine sulfoxide and S-ethyl L-cysteine sulfoxide were substrates but were less suitable than L-cystine. L- and D-cysteine and also cystathionine were not substrates. The purified enzyme (Mr 186,000) was composed of four identical subunits (Mr 45,000) and was pyridoxal 5′-phosphate-dependent.

NON-IDENTITY OF CYSTINE LYASE WTH &β-CYSTATHIONASE IN TURNIP ROOTS

An active praparation of cystine lyase (EC 4.4.1-) was prepared from turnip roots and its substrate specificity examined.Only L-cysteine, cysteine-S-SO3, and the sulphoxides of L-djenkolic acid, S-methyl- and S-ethyl-L-cysteine were substrates.L-Cystathione, L-djenkolic acid, S-methyl- and S-ethyl-cysteines were not cleaved by this enzyme.The Km for L-cystine was 1.3 mM and L-cystathionine acted as an effective competitive inhibitor with a Ki of 0.7 mM.After dialysis against 10 mM potassium phosphate buffer pH 7.5, added pyridoxal phosphate was absolutely necessary for activity.In addition a marked stimulation was observed in the presence of ammonium sulphate.The products of the reaction were cysteine persulphide, pyruvate and presumably ammonia.The persulphide was easily demonstrated by cleavage with CN- to yield SCN- under conditions in which elemental sulphur was unreactive. Key Word Index- Brassica rapa,; Cruciferae; turnip root; cystine lyase; β-cystathionase; cystine degradation.