EXAFS analysis of the active site of the nonmetalloenzyme human prostatic acid phosphatase by means of Cu2+ inactivation

✍ Scribed by Karin Moller; Robert L. Van Etten

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 358 KB
• Volume: 3
• Category: Article
• ISSN: 1075-4261
• DOI: 10.1002/(sici)1520-6343(1997)3:2<85::aid-bspy1>3.0.co;2-r

✦ Synopsis

The enzyme human prostatic acid phosphatase is normally metal-free in its native state but can be stoichiometrically inactivated with cupric acetate. Direct structural evidence is reported for the participation of two histidine residues in the Cu 2/ binding site. X-Ray absorption fine structure spectroscopy (EXAFS) data taken of the CuK-edge reveal that copper is coordinated to five nitrogen or oxygen ligands at 1.99 A ˚. Two of these first shell ligands are part of two histidine amino acid residues with outer shell Cu{C/N distances of 2.96 and 4.08 A ˚. Empirical phase and amplitude functions were successfully used for outer shell fittings. The results are confirmed by comparison with reference structures including L-histidinato-D-histidinato diaquo Cu(II) tetrahydrate. The influence of Cu-imidazole coordination on absorption edge and EXAFS data is discussed. A model of the copper binding site is proposed which involves two histidines present at the active site of enzyme.