The ability of structural analogues of ascorbate to serve as substitutes for this reducing agent in the prolyl 4-hydroxylase reaction was studied. In experiments using the purified enzyme, variations of the compounds' side chain were compatible with co-substrate activity. The presence of very large hydrophobic substituents or a positively charged group caused an increase in the observed Km valu...

Enzyme kinetics are usually described by the Michaelis-Menten equation, where the time-dependent decrease of substrate (-dS/dt) is a hyperbolic function of maximal velocity (Vmax), Michaelis constant (Km), and amount of substrate (S). Because the Michaelis-Menten function in its most general meaning requires an assumption of steady-state, it is less curvilinear than true enzyme kinetics. A satu...

Crude wild pear lipoxygenase (LOX) from ripe Kurdistan wild pears was used in this study. Extracted crude LOX was assayed spectrophotometrically for raw, ripe wild pear lipoxygenase and after 7-day storage. The effects of different buffers and pHs, substrate preparations, temperature, inhibitors and metal ions on LOX activity were evaluated at three conditions. The enzyme was most active with H...

The effect of electrostatic screening of fixed negative charges on uncoupled mitochondrial electron transport was investigated with substrates with different charge and different sites of donation of electrons to the electron-transport chain of Jerusalem-artichoke (Helianthus tuberosus L.) mitochondria. Duroquinol (neutral substrate) was oxidized with a pH optimum of 7.6-7.8. The addition of ca...

Objective(s): Enzyme immobilization via nanoparticles is perfectly compatible against the other chemical or biological approximate to improve enzyme functions and stability. In this study lactoperoxidase was immobilized onto silica-coated magnetite nanoparticles to improve enzyme properties in the presence of cadmium chloride as an inhibitor. Materials and Methods:  The process consists of the ...

The roles of Arg-104 and Arg-225 located in the 2-kinase domain of the bifunctional enzyme 6-phosphofructo-2-kinase (PFK-2)/fructose-2,6-bisphosphatase (FBPase-2) have been studied by site-directed mutagenesis. In recombinant rat liver PFK-2/FBPase-2, mutation of Arg-225 to Ser increased the Km of PFK-2 for fructose-6-phosphate (Fru-6-P) 7-fold at pH 6 and decreased PFK-2 activity at suboptimal...