title: Purification and some properties of rabbit C1 inactivator.
abstract: C1 inactivator (C1 INA) was highly purified from rabbit serum. C1 INA thus purified was a single polypeptide chain with a molecular weight of 105,000 or 140,000, as estimated by SDS-polyacrylamide gel electrophoresis or gel filtration on Sephadex G-200, respectively. It inhibited rabbit and also human C1, when the C1 activities were measured in terms of hydrolyses of acetylglycyl-L-lysine methylester, N-alpha-acetyl-L-arginine methylester and N-alpha-acetyl-L-tyrosine ethylester. These properties showed that rabbit C1 INA bears a marked structural similarity to human C1 INA. Furthermore, rabbit C1 INA was capable of inhibiting similarly both rabbit C1s and its active fragment lacking a half of the H chain of C1s, indicating that deletion of a half of the H chain did not affect the susceptibility of C1s to the inhibitory activity of C1 INA.
mesh_terms: D000818:Animals; D003174:Complement C1 Inactivator Proteins / Q000097:blood / Q000302:isolation & purification; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D011480:Protease Inhibitors; D011817:Rabbits; D013045:Species Specificity
chemical_list: D003174:Complement C1 Inactivator Proteins; D011480:Protease Inhibitors