Structural Analysis of Aliphatic versus Aromatic Substrate Specificity in a Copper Amine Oxidase from Hansenula polymorpha

详细信息    查看全文

• 作者：Valerie J. Klema ; Corinne J. Solheid ; Judith P. Klinman ; Carrie M. Wilmot
• 刊名：Biochemistry
• 出版年：2013
• 出版时间：April 2, 2013
• 年：2013
• 卷：52
• 期：13
• 页码：2291-2301
• 全文大小：479K
• 年卷期：v.52,no.13(April 2, 2013)
• ISSN：1520-4995

文摘

Copper amine oxidases (CAOs) are responsible for the oxidative deamination of primary amines to their corresponding aldehydes. The CAO catalytic mechanism can be divided into two half-reactions: a reductive half-reaction in which a primary amine substrate is oxidized to its corresponding aldehyde with the concomitant reduction of the organic cofactor 2,4,5-trihydroxyphenylalanine quinone (TPQ) and an oxidative half-reaction in which reduced TPQ is reoxidized with the reduction of molecular oxygen to hydrogen peroxide. The reductive half-reaction proceeds via Schiff base chemistry, in which the primary amine substrate first attacks the C5 carbonyl of TPQ, forming a series of covalent Schiff base intermediates. The X-ray crystal structures of copper amine oxidase-1 from the yeast Hansenula polymorpha (HPAO-1) in complex with ethylamine and benzylamine have been determined to resolutions of 2.18 and 2.25 脜, respectively. These structures reveal the two amine substrates bound at the back of the active site coincident with TPQ in its two-electron-reduced aminoquinol form. Rearrangements of particular amino acid side chains within the substrate channel and specific protein鈥搒ubstrate interactions provide insight into the substrate specificity of HPAO-1. These changes begin to account for this CAO鈥檚 kinetic preference for small, aliphatic amines over the aromatic amines or whole peptides preferred by some of its homologues.