Enzyme bovine serum amine oxidase

In enzyme catalysis, 249, 373-397 [bovine serum amine oxidase, 249, 393-394 coupled motion and, 249, 386-388 demonstration, 249, 374-386 (breakdown of rule of geometric mean in,... 

As for deaminase, the kinetic analysis suggests a partial mixed-type inhibition mechanism. Both the Ki value of the inhibitor and the breakdown rate of the enzyme-substrate-inhibitor complex are dependent on the chain length of the PolyP, thus suggesting that the breakdown rate of the enzyme-substrate-inhibitor complex is regulated by the binding of Polyphosphate to a specific inhibitory site (Yoshino and Murakami, 1988). More complicated interactions were observed between PolyP and two oxidases, i.e. spermidine oxidase of soybeen seedling and bovine serum amine oxidase. PolyP competitively inhibits the activities of both enzymes, but may serve as an regulator because the amino oxydases are also active with the polyamine-PolyP complexes (Di Paolo et al., 1995). 

Janes, S. M., Mu, D., Wemmer, D., Smith, A. J., Kaur, S., Maltby, D., Burlingame, A. L., and Klinman, J. P., 1990, A new redox cofactor in eukaruotic enzymes 6-hydroxydopa at the active site of bovine serum amine oxidase. Science, 248 981n987. 

Structure of the active center. The active centers of this dimeric enzyme are so well embedded into its protein structure that they are inaccessible to the solvent. The two centers are situated approximately 30 A apart from each other but connected by /3-strands. The active center consists of a type 2 copper center and a cofactor. Sequence comparisons have established that the residues His 8, His 246, and His 357 coordinate the copper ions in both yeast and plants (e.g., lentil seeds) [120,122]. The participating cofactor is typical for amine oxidases, diamine oxidases, and lysyl oxidases but has not yet been found in any other protein - 2,4,5-trihydroxy-phenylalanine quinone [123, 124] (also known as TOPA-quinone, TPQ or 6-hydroxy-DOPA quinone), an internal cofactor which is created by post-translational modification of the tyrosine in position 387 [120]. The consensus sequence of the amino acids neighboring the TOPA cofactor are conserved in all known amine oxidases - Asn-TOPA-Asp/Glu [113,120, 123,125-127]. The positions of the histidine ligands relative to TOPA quinone are conserved in all known amine oxidases as well. The chain lengths of the amine oxidase monomers vary according to the organism of origin 692 residues in yeast [128], 762 in bovine serum amine oxidase [128,129] and 569 in the enzyme from lentil seeds [120,130]. 

The copper can be reversibly removed from the active site by reaction with diethyldithiocarbamate under non-reducing conditions [86-88], or by cyanide after reduction by dithionate to Cu(I) [78]. The catalytic activity of the enzyme can be restored with high yield by addition of free Cu(II) ions to the apoenzyme [78,86]. In the case of pea seedling amine oxidase, addition of other bivalent metal ions does not lead to reactivation [86]. However the activity can be partially restored (from 15%) for the amine oxidase from bovine plasma by adding Co(II) [89]. Addition of Co(II) and Ni(II) can restore the original spectrum of the native enzyme with bovine serum amine oxidase reduced by dithionate [90]. 

Copper-depleted bovine serum amine oxidase has been recently reconstituted with Co(II) ions. The benzylamine oxidase activity of the enzyme was increased to 20% on incorporation of cobalt. Furthermore, Co(II) restored to nearly native level the intensity of the absorption spectrum and the reactions with phenylhydrazine or benzylhydrazine, which had been slowed down or abolished, respectively, in Cu(II)-depleted samples. The amine oxidase activity of the Co(II)-derivative, which cannot form a semiquinone radical as an intermediate of the... 

Later, the presence of topa quinone was accordingly confirmed in the amine oxidases from porcine serum and kidney and pea seedling by resonance Raman spectrometry of active-site labeled peptides [48]. Comparison of amino acid sequences of these peptides with the sequences of those from bovine plasma and H. polymorpha amine oxidases demonstrated the presence of a consensus sequence Asp-TPQ-Asp/Glu as shown in Fig. (1). Using the pH-dependent shift of the absorption maximum of the enzyme p-nitrophenylhydrazone, which is considered to be a reliable indirect proof, the presence of topa quinone was also shown... 

---