Cystalysin, a 46-kDa L-cysteine desulfhydrase from Treponema denticola: biochemical and biophysical characterization.
Cystalysin, a 46-kDa L-cysteine desulfhydrase from Treponema denticola: biochemical and biophysical characterization.
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Cystalysin，一种来自密螺旋体的 46 kDa L-半胱氨酸脱硫酶：生化和生物物理特征。
DOI：
10.1086/515164
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Holt,SC
中科院分区：
文献类型：
--
作者：
Chu,L;Ebersole,JL;Kurzban,GP;Holt,SC
齿密螺旋体ATCC 35404编码的一种46 kDa的溶血蛋白Cystalysin在大肠杆菌中高效表达。Cystalysin溶解红细胞，将血红蛋白氧化成硫化血红蛋白和高铁血红蛋白，并从选定的含S的化合物(如半胱氨酸)中去除产生硫化氢、氨和丙酮酸的巯基和氨基。以L-半胱氨酸为底物，半胱氨酸酶服从米氏动力学。半胱硫氨酸和S-氨基乙基-L-半胱氨酸也是底物。几个小的α-氨基酸被发现是胱氨酸酶的竞争性抑制剂。β-巯基乙醇可提高该酶的活性，但不能被TLCK(Nα-对甲苯磺酰基-L-赖氨酸氯甲基酮)、链霉酶或蛋白酶K抑制，表明该功能部位受到物理保护或位于多肽的一小段中。我们推测，Cystalysin是一种含有吡哆醛-5-磷酸的酶，具有αC-N和βC-S裂解酶(胱硫酶)的活性。由于在深牙周袋中发现了大量的H_2S，因此这种代谢酶就不再存在了。在体内也可以作为一种重要的毒力分子发挥作用。
A 46-kDa hemolytic protein referred to as cystalysin, fromTreponema denticolaATCC 35404, was characterized and overexpressed inEscherichia coliLC-67. Cystalysin lysed erythrocytes, hemoxidized hemoglobin to sulfhemoglobin and methemoglobin, and removed the sulfhydryl and amino group from selected S-containing compounds (e.g., cysteine) producing H2S, NH3, and pyruvate. WithL-cysteine as substrate, cystalysin obeys Michaelis-Menten kinetics. Cystathionine and s-aminoethyl-L-cysteine were also substrates. Several of the small alpha amino acids were found to be competitive inhibitors of cystalysin. The enzymatic activity was increased by β-mercaptoethanol and was not inhibited by the proteinase inhibitor TLCK (Nα-p-tosyl-L-lysine chloromethyl ketone), pronase, or proteinase K, suggesting the functional site was physically protected or located in a small fragment of the polypeptide. We hypothesize that cystalysin is a pyridoxal-5-phosphatecontaining enzyme with the activity of an αC-N and βC-S lyase (cystathionase). Since high amounts of H2S have been reported in deep periodontal pockets, this metabolic enzyme fromT. denticolamay also function in vivo as an important virulence molecule.