The metal function in the reactions of bovine serum amine oxidase with substrates and hydrazine inhibitors.
Bovine serum amine oxidase (BSAO) reacts with 2-hydrazinopyridine, which binds the organic co-factor 2,4,5-trihydroxyphenylalanine quinone, forming a band at 435 nm. The band shifts to 526 nm around 60 degrees C, to 415 nm upon denaturation, but only shifts to 429 nm upon Cu2+ depletion. Its wavelength and intensity suggest that the adduct has the azo conformation, whilst the same adduct of crystalline Escherichia coli amine oxidase (ECAO) shows the hydrazone conformation in the X-ray structure. The steady state kinetics of aminomethyl- and aminoethylpyridines confirm that the formation of the product Schiff base, analogous to the azo form of the 2-hydrazinopyridine adduct, is not hindered in solution. The structural stability of the adduct in the absence of Cu2+ is taken to imply hydrogen bonding of the pyridyl nitrogen to a conserved aspartate, as in the ECAO adduct. Thus the ECAO adduct provides a good model for a transient intermediate leading to formation of the BSAO azo adduct. On the basis of this model and of the catalytic competence of Co(2+)-substituted BSAO, confirmed by the present data, a catalytic reaction scheme is proposed.
De Matteis
G
G
Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Università La Sapienza, Rome, Italy.
Agostinelli
E
E
Mondovì
B
B
Morpurgo
L
L
D006631:Amine Oxidase (Copper-Containing) / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D003035:Cobalt / Q000737:chemistry / Q000378:metabolism; D003300:Copper / Q000737:chemistry / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D007700:Kinetics; D008670:Metals / Q000378:metabolism*; D011728:Pyridones / Q000737:chemistry / Q000494:pharmacology
D004791:Enzyme Inhibitors; D008670:Metals; D011728:Pyridones; D003035:Cobalt; C062607:2-hydrazinopyridine; D003300:Copper; D006631:Amine Oxidase (Copper-Containing)