Angiotensinogen cleavage by renin: importance of a structurally constrained N-terminus.
Angiotensinogen, a plasma serpin, functions as a donor of the decapeptide angiotensin I, which is cleaved from the N-terminus by renin. To assess the contribution of the serpin framework to peptide cleavage we produced a chimaeric molecule of alpha1-antitrypsin carrying the angiotensinogen N-terminus and determined the kinetic parameters for angiotensin I release. The Km for plasma angiotensinogen was 18-fold lower than for the chimaeric protein while the catalytic efficiency was four-fold higher. We also show that Cys-18 participates in a disulphide bond and propose that constraints on the N-terminus profoundly affect the interaction with renin.
Department of Haematology, University of Cambridge, MRC Centre, UK.
R M
RM
Streatfeild-James
D
D
Williamson
R N
RN
Pike
D
D
Tewksbury
R W
RW
Carrell
P B
PB
Coughlin
D000595:Amino Acid Sequence; D000808:Angiotensinogen / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D003001:Cloning, Molecular; D003545:Cysteine; D004220:Disulfides; D004926:Escherichia coli; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010047:Ovalbumin / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012083:Renin / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D000515:alpha 1-Antitrypsin / Q000737:chemistry / Q000378:metabolism
D004220:Disulfides; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D000515:alpha 1-Antitrypsin; D000808:Angiotensinogen; D010047:Ovalbumin; D012083:Renin; D003545:Cysteine