STREPTOCOCCAL-C5A PEPTIDASE IS A HIGHLY SPECIFIC ENDOPEPTIDASE
STREPTOCOCCAL-C5A PEPTIDASE IS A HIGHLY SPECIFIC ENDOPEPTIDASE
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DOI：
10.1128/iai.60.12.5219-5223.1992
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发表时间：
1992-12-01
影响因子：
3.1
通讯作者：
HANDLEY, J
中科院分区：
文献类型：
--
作者：
CLEARY, PP;PRAHBU, U;HANDLEY, J
从C5a的20个c端残基对应的合成肽段中合成的链球菌C5a肽酶（SCPA）裂解产物的组成分析表明，裂解的目标位点是His-Lys，而不是之前认为的Lys-Asp。用Gln取代赖氨酸的C5a肽类似物也可被SCPA切割。这证实了His-Lys而不是Lys-Asp是可剪键。组氨酸的切割是不寻常的，但与B群链球菌产生的肽酶的切割相同。天然C5蛋白也对SCPA具有抗性，这表明在C5转化酶水解裂解蛋白质之前，His-Lys键是不可接近的。这些实验表明，链球菌C5a肽酶对C5a具有高度特异性，表明其功能不仅仅是处理代谢消耗的蛋白质，而是主要消除炎症灶的趋化信号。
Compositional analysis of streptococcal C5a peptidase (SCPA) cleavage products from a synthetic peptide corresponding to the 20 C-terminal residues of C5a demonstrated that the target cleavage site is His-Lys rather than Lys-Asp, as previously suggested. A C5a peptide analog with Lys replaced by Gln was also subject to cleavage by SCPA. This confirmed that His-Lys rather than Lys-Asp is the scissile bond. Cleavage at histidine is unusual but is the same as that suggested for a peptidase produced by group B streptococci. Native C5 protein was also resistant to SCPA, suggesting that the His-Lys bond is inaccessible prior to proteolytic cleavage by C5 convertase. These experiments showed that the streptococcal C5a peptidase is highly specific for C5a and suggest that its function is not merely to process protein for metabolic consumption but to act primarily to eliminate this chemotactic signal from inflammatory foci.