The disulfide bond pattern of catrocollastatin C, a disintegrin-like/cysteine-rich protein isolated from Crotalus atrox venom

The disulfide bond pattern of catrocollastatin-C was determined by N-termin al sequencing and mass spectrometry. The N-terminal disintegrin-like domain is a compact structure including eight disulfide bonds, seven of them in t he same pattern as the disintegrin bitistatin. The protein has two extra cy steine residues (XIII and XVI) that form an additional disulfide bond that is characteristically found in the disintegrin-like domains of cellular met alloproteinases (ADAMs) and PIII snake venom Zn-metalloproteinases (SVMPs), The C-terminal cysteine-rich domain of catrocollastatin-C contains five di sulfide bonds between nearest-neighbor cysteines and a long range disulfide bridge between CysV and CysX. These results provide structural evidence fo r a redefinition of the disintegrin-like and cysteine-rich domain boundarie s. An evolutionary pathway fur ADAMs, PIII, and PII SVMPs based on disulfid e bond engineering is also proposed.