Mechanistic investigation of hemicellulose degrading enzymes

Hydrolysis of substituted and unsubstituted pyridinium and isoquinolinium derivatives of xylopyranosyl pyridinium salt by {dollar}beta{dollar} xylosidase form B. pumilus were measured. Similarly the hydrolysis of {dollar}beta{dollar}-glucosyl salts by {dollar}beta{dollar} glucanase from Sporotrichum dimorphosporum and the hydrolysis of {dollar}alpha{dollar}-glucosyl salts by glucoamylase from Aspergilus niger were measured. The efficient hydrolysis of these salts by these inverting enzymes precludes the ring opening mechanism proposed by Franck for the hydrolysis of these glycosides.; The hydrolysis of glycosyl monofluoride and difluoride by {dollar}alpha{dollar} galactosidase from P. cinnabarinus and {dollar}beta{dollar} glucanase from Sporotrichum dimorphosporum was measured. The ratio for the hydrolysis of monofluoride to difluoride measure the extent of oxocarbonium ion character at the transition state of these enzymes during hydrolysis of glycosides.; Enzyme activated irreversible inactivation of {dollar}alpha{dollar}-galactosidase of Pycnoporus cinnabarinus by triazene was measured at pH range from 6.5-8.5. The pH dependence of the efficiency of capture of diazonium ion by enzyme suggest that capture of the diazonium ion is pH dependent rather than the chemical event that generates it near the active site.