The effect of residue 1106 on the thioester‐mediated covalent binding reaction of human complement protein C4 and the monomeric rat α‐macroglobulin α1I3

FEBS Letters

Alex Law, S.K.¹  Dodds, Alister W.¹  Chu, Charleen T.²  Ren, Xiang-Dong¹  Enghild, Jan J.² 

[1] MRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK;Department of Pathology, Box 3712, Duke University Medical Center, Durham, NC 27710, USA

关键词: Complement;    α-Macroglobulin;    Thioester;    Covalent binding;    α1I3;    α1-inhibitor 3;    α2M;    α2macroglobulin;    C1s;    activated complement subcomponent of C1;    EA;    sheep erythrocytes coated with sensitizing antibody;    EAC1;    EA with activated C1 on the cell surface;    HNE;    human neutrophil elastase;   

DOI  :  10.1016/0014-5793(95)00606-A

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The histidine at position 1106 of the C4B isotype of human complement is involved in catalyzing the covalent binding of the thioester to glycerol and water. By replacing the histidine with other residues, it was found that tyrosine is also capable of mediating the reaction. We propose that they act as nucleophiles by first attacking the thioester, upon activation, to form acyl intermediates, which subsequently react with the hydroxyl groups of glycerol or water. The monomeric α-macroglobulin, α₁I3 of the rat, was also studied. Unlike α₂-macroglobulin, which is a tetramer, α₁I3 has binding properties similar to those of C4A.

【 授权许可】

Unknown