Electron spin resonance investigation of the copper(II)–β-glucosidase interaction in aqueous solution

Abstract

Electron spin resonance spectroscopy has been used to investigate the coordination behaviour of β-glucosidase aqueous solutions in the presence of divalent metal ions such as copper(II). The strong affinity of the paramagnetic metal ions towards the enzyme was verified; two metal–enzyme interaction sites were characterized as a function of pH and temperature and a N₃/O₁ copper(II) atom donor set proposed. In the presence of cellobiose solutions the Cu^II–β-glucosidase electron spin resonance parameters were unaffected in the range of pH and molar ratios investigated.