Characterization of the haemoglobin-mediated inhibition of the enzymatic activity of bovine serum amine oxidase.
Haemoglobin has been previously identified as responsible for the decreased enzymatic activity of copper bovine serum amine oxidase (BSAO) in suspensions of human or bovine hemolyzed erythrocytes [Marcocci, L., Pietrangeli, P., Befani, O., Mavelli, I., & Mondovi', B. (1991b) Life Chem. Report, 9, 171-177]. This is confirmed by present results on bovine methaemoglobin. Bovine globin and horse skeletal muscle mioglobin showed a similar inhibiting ability, but neither bovine serum albumin nor cytochrome c inhibited BSAO activity under the same experimental conditions. The inhibitory effect of bovine haemoglobin was dependent on pH only at high buffer ionic strength. It was highest in physiological conditions (PBS) where haemoglobin acted as a reversible non competitive inhibitor of BSAO activity, with apparent Ki of 0.5 mM at 37 degrees C. The inhibition was unaffected by partial BSAO deglycosylation (40% of glucidic residues removed) but decreased when haemoglobin lysine groups were derivatised using citraconic anhydride. A possible molecular mechanism underlying the inhibitory effect is discussed.
Pietrangeli
P
P
Department of Biochemical Sciences A Rossi Fanelli, University of Rome La Sapienza, Rome, Italy.
Marcocci
L
L
Morpurgo
L
L
Befani
O
O
Wang
X
X
Mondovi
B
B
D006631:Amine Oxidase (Copper-Containing); D000818:Animals; D001596:Benzylamines / Q000378:metabolism; D001798:Blood Proteins / Q000037:antagonists & inhibitors; D002417:Cattle; D006801:Humans; D007700:Kinetics; D008706:Methemoglobin / Q000378:metabolism*; D008970:Molecular Weight; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000037:antagonists & inhibitors* / Q000097:blood; D013379:Substrate Specificity
D001596:Benzylamines; D001798:Blood Proteins; D008706:Methemoglobin; C030796:benzylamine; D006631:Amine Oxidase (Copper-Containing); D000587:Oxidoreductases Acting on CH-NH Group Donors