Purification and Characterization of Cystine Lyase a from Broccoli Inflorescence
作者:Koji Ukai、Jiro Sekiya
DOI:10.1271/bbb.61.1890
日期:1997.1
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.
从西兰花(Brassica oleracea var. italica)的花序中,通过对反应产物与溴代二溴萘的衍生化作用,利用一种灵敏的检测方法,将三种同工酶之一的一种降解L-胱氨酸的酶纯化至均一性。通过液相色谱-质谱联用和高分辨率质谱分析结果发现,具有巯基的反应产物为硫代半胱氨酸。丙酮酸也是反应产物,其生成量与L-胱氨酸等摩尔。纯化的酶催化L-胱氨酸的β-消去反应,产生硫代半胱氨酸、丙酮酸,可能还有氨,因此它是胱氨酸裂解酶a。L-胱氨酸而非D-胱氨酸是该酶的底物。S-甲基-L-半胱氨酸亚砜和S-乙基-L-半胱氨酸亚砜是底物,但不如L-胱氨酸合适。L-和D-半胱氨酸以及胱硫醚不是底物。纯化的酶(分子量186,000)由四个相同的亚基(分子量45,000)组成,并依赖于吡哆醛5'-磷酸。
Iterative synthetic strategies and gene deletant experiments enable the first identification of polysulfides in <i>Saccharomyces cerevisiae</i>
作者:Lisa I. Pilkington、Rebecca C. Deed、Katie Parish-Virtue、Chien-Wei Huang、Michelle E. Walker、Vladimir Jiranek、David Barker、Bruno Fedrizzi
DOI:10.1039/c9cc03020d
日期:——
Polysulfides, potential signalling molecules, were synthesised and then found and explored for the first time in yeast.
聚硫化物,潜在的信号分子,首次在酵母中被合成、发现并探索。
C-S bond cleavage by a polyketide synthase domain
作者:Ming Ma、Jeremy R. Lohman、Tao Liu、Ben Shen
DOI:10.1073/pnas.1508437112
日期:2015.8.18
Leinamycin (LNM) is a sulfur-containing antitumorantibiotic 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...
Stereoselective Biocatalytic α‐Deuteration of L‐Amino Acids by a Pyridoxal 5’‐Phosphate‐Dependent Mannich Cyclase
作者:Jinmin Gao、Chen Zhou、Yang Hai
DOI:10.1002/cbic.202300561
日期:2023.12
A PLP-dependent Mannich cyclase LolT is repurposed for α-deuteration of amino acids. Complete deuteration can be achieved with diverse L-amino acids bearing assorted functional groups, e. g. from lysine to glutamic acid. The broad substratescope and strict stereoselectivity make LolT a powerful biocatalyst for preparation of α-deuterated L-amino acids.
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.