Title : SP-40,40, a
protein involved in the control of the complement pathway, possesses a unique array of disulphide bridges
Abstract :
- SP-40,40 is a two-chain serum protein which acts in vitro as a potent inhibitor of the assembly of the membrane attack complex of human complement
- It contains 10 cysteine residues , the numbers and locations of which are conserved in several mammalian species
- Evidence is presented that all the cysteine residues cysteine residues are involved in interchain (alpha-beta) disulphide bonds
- There are no free cysteine residues
- The disulphide bond motif established in this study for SP-40,40 is unique and bears no obvious homology to those complement components whose disulphide bonds have been assigned, nor is there any homology apparent between SP-40,40 and other multi-chain proteins containing disulphide bonds