Copper amine oxidase

Copper amine oxidases structure and function. B. Mondovi and P. Riccio, Adv. Inorg. Biochem., 1984, 6, 225 (116). 

Divalent Co substitution in copper amine oxidase revealed 19% of the native specific activity (for MeNH2) and 75% of the native reactivity toward phenylhydrazine. The major cause of this was a 68-fold increase in Km for 02. These investigations support the idea that electrons flow directly to bound 02 without the need for a prior metal reduction and that the Cu does not redox cycle but simply provides electrostatic stabilization during reduction of 02 to 02-. 1211... 

Laurenzi M, Tipping AJ, Marcus SE, Knox JP, Federico R, Angelini R, McPherson MJ (2001) Analysis of the distribution of copper amine oxidase in cell walls of legume seedlings. Planta 214 37 4-5... 

Rea G, Metoui O, Infantino A, Federico R, Angelini R (2002) Copper amine oxidase expression in defense responses to wounding and Ascochyta rabiei invasion. Plant Physiol 128 865-875 Roeder V, Collen J, Rousvoal S, Corre E, Leblanc C, Boyen C (2005) Identification of stress gene transcripts in Laminaria digitata (Phaeophyceae) protoplast cultures by Expressed Sequence Tag analysis. J Phycol 41 1227-1235... 

Klinman JP. 2003. The multi-functional topa-quinone copper amine oxidases. Biochim Biophys Acta 1647 131. 

M. Mure, S.A. Mills, J.P. Klinman, Catalytic mechanism of the topa quinone containing copper amine oxidases. Biochemistry 41 (2002) 9269-9278. 

Lysine tyrosylquinone (LTQ). Another copper amine oxidase, lysyl oxidase, which oxidizes side chains of lysine in collagen and elastin (Eq. 8-8) contains a cofactor that has been identified as having a lysyl group of a different segment of the protein in place of the - OH in the 2 position of topaquinone.465 Lysyl oxidase plays an essential role in the crosslinking of collagen and elastin. 

Mechanisms. Studies of model reactions473-476 and of electronic, Raman,456 477 478 ESR,479/480 and NMR spectra and kinetics481 have contributed to an understanding of these enzymes.459 461 464 482 483 For these copper amine oxidases the experimental evidence suggests an aminotransferase mechanism.450 453 474 4743 d Tire structure of the E.coli oxidase shows that a single copper ion is bound by three histidine imidazoles and is located adjacent to the TPQ (Eq. 15-53). Asp 383 is a conserved residue that may be the catalytic base in Eq. 15-53.474b A similar mechanism can be invoked for LTQ and TTQ. 

A fourth possibility is the generation of H202 via oxidation of putrescine (butane-1,4-diamine 2.56). This reaction is catalyzed by copper amine oxidase (E.C. 1.4.3.6). Copper amine oxidases are homodimers in which each unit contains a copper ion and a 1,3,5-trihydroxyphenylalanine quinine co-factor. In plants copper amine oxidases generally oxidize putrescine to 4-aminobutanal (2.57). This latter compound undergoes spontaneous cyclization to A1 pyrroline (2.58), ammonia, and H202, as shown in Figure 2-12 (Medda et al., 1995). 

Figure 2-12. Formation of H202 via oxidation of putrescine by copper amine oxidase.

Medda, R., Padiglia, A., Pedersen, J. Z., Rotilio, G., Finazzi Agro, and Floris, G, 1995, The reaction mechanism of copper amine oxidase detection of intermediates by the use of substrates and inhibitors, Biochem. 34 16375-16381. 

The copper amine oxidases (CAOs) catalyze the oxidative deamination of primary amines to aldehydes and the production of H202 for use in cell signaling. The... 

FIGURE 9.11 Proposed inner- and outer-sphere pathways in copper amine oxidases obscured by the rapid internal redox equilibrium. 

Mills S. A. Klinman J. P. Evidence against reduction of Cu2+ to Cu+ during dioxygen activation in a copper amine oxidase from yeast. J. Am. Chem. Soc. 2000, 122, 9897-9904. 

Mills S. A. Goto Y. SuQ. Plastino J. Klinman J. P. Mechanistic comparison of the cobalt-substituted and wild-type copper amine oxidase from Hansenula polymorpha. Biochemistry 2002, 41, 10577-10584. 

Takahashi K. Klinman J. P. Relationship of stopped flow to steady state parameters in the dimeric copper amine oxidase from Hansenula polymorpha and the role of zinc in inhibiting activity at alternate copper-containing subunits. Biochemistry 2006, 45, 4683 1694. 

Mukherjee A. Smirnov V. V. Land M. P. Brown D. E. Shepard E. M. Dooley D. M. Roth J. P. Inner-sphere mechanism for molecular oxygen reduction catalyzed by copper amine oxidases. J. Am. Chem. Soc. 2008, 130, 9459-9473. 

FIGURE 13. Species identified in the reaction cycle of copper amine oxidases. Oxidised, resting state enzyme (1) reacts with substrate to form a substrate Schiff base (2). Proton abstraction by the active site base (Asp383 in ECAO) leads, via a carbanion intermediate (3) to the product Schiff base (4). Hydrolysis releases the product aldehyde, leaving reduced cofactor in equilibrium between aminoquinol/Cu (S) and semiquinone/Cu (6). The reduced cofactor is reoxidised by molecular oxygen, releasing ammonium ions and hydrogen peroxide. (Modified from Wilmot et al., 1999 with permission). 

Cai, D. Y., and Klinman, J. P., 1994, Copper amine oxidase heterologous expression, purification and characterisation of an active enzyme in Saccharomyces cerevisiae. Biochemistry 33 7647n7653. 

Coleman, A. A., Hindsgaul, O., and Palcic, M. M., 1989, Stereochemistry of copper amine oxidase reactions, J. Biol. Chem. 264 19500919505. 

Lee, Y., and Sayre, L. M., 1995, Model studies on the quinone-containing copper amine oxidases unambiguous demonstration of a transamination mechanism, J. Amer. Chem. Soc. 117 11823nll828. 

Li, R. B., Klinman, J. P., and Mathews, F. S., 1998, Copper amine oxidase from Hansenula poly-morpha the crystal structure determined at 2. 4 resolution reveals the active conformation, Structure 6 293n307. 

Medda, R., Padiglia, A., and Floris, G., 1995, Plant copper amine oxidases. Phytochemistry 39 ln9. 

Mu, D., Janes, S. M., Smith, A. J., Brown, D. E., Dooley, D. M., and Klinman, J. P., 1992, Tyrosine codon corresponds to TOPA quinone at the active site of copper amine oxidases, J. Biol. Chem. 267 7979n7982. 

Plastino, J., Green, E. L., Sanders-Loehr, J., and Klinman, J. P., 1999, An unexpected role for the active site base in cofactor orientation and flexibility in the copper amine oxidase from Hansenula polymorpha. Biochemistry, 820488216D. 

Ruggiero, C. E., and Dooley, D. M., 1999, Stoichiometry of the TOPA quinone biogenesis reaction in copper amine oxidases, Biochemistry 38 2892n2898. 

Most copper-containing oxygenases and oxidases use multiple metal centers to conduct their biotransformations. Copper amine oxidases (CAO) and galactose oxidase (GalO), instead, employ posttranslationahy derived amino acid side chains as cofactors to supply additional electrons (24). 

Figure 5 Illustration of possible partial reaction cycles of some copper- and flavin-dependent oxidase enzymes, (a) Copper amine oxidase 30, 31 (b) galactose oxidase (32) (c) catechol oxidase (10) (d) multicopper oxidases (10) (e) flavin oxidases (30) (f) cytochrome c oxidase (38).

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