Specificity and mechanism of action of metal ions in yeast enolase

AbstractYeast enolase requires one mole/subunit of an ‘activating’ metal ion (e.g. Mg2+, Mn2+) in ‘conformational’ sites. This enables substrate/product or analogues to be bound in distorted configurations. ‘Nonactivating’ metal ions (e.g. Ca2+, Tb2+) enable binding to occur but without the distortion. Activating metal ions appear to prefer octahedral coordination. Substrate/product or analogue binding enables one mole/subunit of additional, ‘catalytic’ metal ion to bind, which produces activity if the conformational metal ion is an ‘activator’. Catalytic metal ion may bind directly to the carboxyl of substrate/product. We suggest that a molecule of water which is bound to conformational metal ion participates in actual bond breaking by donation or acceptance of protons to and from substrate/product. It is possible that metal ion-bound water is far more important in enzymatic catalysis that previously recognized.EnolaseSpecificityYeas

Parameter identification for an abstract Cauchy problem by quasilinearization

A parameter identification problem is considered in the context of a linear abstract Cauchy problem with a parameter-dependent evolution operator. Conditions are investigated under which the gradient of the state with respect to a parameter possesses smoothness properties which lead to local convergence of an estimation algorithm based on quasi-linearization. Numerical results are presented concerning estimation of unknown parameters in delay-differential equations