TY - JOUR
T1 - Methionine modification impairs the C5-cleavage function of cobra venom factor-dependent C3/C5 convertase
AU - Fu, Qinglan
AU - McPhie, Peter
AU - Channe Gowda, D.
PY - 1998/6
Y1 - 1998/6
N2 - The complement-mediated lysis of guinea pig erythrocytes by cobra venom factor (CVF) decreased by 50-60% within 2 min of treatment with 5 mM sodium periodate at 0°C. This loss of activity paralleled modification of 3-4 Met; other amino acids and sugar residues of the oligosaccharide chains were not affected. Treatment with N-chlorosuccinimide or chloramine-T under conditions that specifically modified 3-4 readily-oxidizable Met also caused 50-60% loss of CVF activity. The secondary structure of CVF was not altered by these modifications. Methionine-modified CVF (MetCVF) supported the cleavage of factor B by factor D with equal efficiency as that of untreated CVF to form C3/C5 convertase (MetCVF,Bb) of the alternative pathway. MetCVF,Bb and CVF,Bb were indistinguishable with respect to C3 cleavage. However, the C5-cleavage ability of MetCVF,Bb was significantly lower than that of CVF,Bb. These results suggest the involvement of Met in CVF binding of C5.
AB - The complement-mediated lysis of guinea pig erythrocytes by cobra venom factor (CVF) decreased by 50-60% within 2 min of treatment with 5 mM sodium periodate at 0°C. This loss of activity paralleled modification of 3-4 Met; other amino acids and sugar residues of the oligosaccharide chains were not affected. Treatment with N-chlorosuccinimide or chloramine-T under conditions that specifically modified 3-4 readily-oxidizable Met also caused 50-60% loss of CVF activity. The secondary structure of CVF was not altered by these modifications. Methionine-modified CVF (MetCVF) supported the cleavage of factor B by factor D with equal efficiency as that of untreated CVF to form C3/C5 convertase (MetCVF,Bb) of the alternative pathway. MetCVF,Bb and CVF,Bb were indistinguishable with respect to C3 cleavage. However, the C5-cleavage ability of MetCVF,Bb was significantly lower than that of CVF,Bb. These results suggest the involvement of Met in CVF binding of C5.
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U2 - 10.1080/15216549800202502
DO - 10.1080/15216549800202502
M3 - Article
C2 - 9635137
AN - SCOPUS:0031840057
SN - 1039-9712
VL - 45
SP - 133
EP - 144
JO - Biochemistry and Molecular Biology International
JF - Biochemistry and Molecular Biology International
IS - 1
ER -