Unveiling cofactor inhibition mechanisms in horse liver alcohol dehydrogenase: An allosteric driven regulation

Horse Liver Alcohol Dehydrogenase (HLADH) is an extensively studied enzyme isolated from equine liver tissue, and holds a central role in numerous enzymatic processes, underscoring the need for thorough investigation. This study delves into the kinetic behavior and structural dynamics of HLADH, shedding light on complex mechanisms governing its catalytic activity and interactions with the cofactor. Notably, deviations from traditional Michaelis–Menten kinetics are observed, manifesting as a slowdown in catalytic rate under high NADH concentrations. Utilizing molecular dynamics simulations, an allosteric site is identified, clarifying how excessive cofactor levels impact protein dynamics and catalytic properties. Structural alterations induced by inhibitory NADH concentrations are revealed, indicating reduced protein flexibility and modifications in catalytic cavity size, thereby elucidating the inhibitory mechanism at high cofactor concentrations. This comprehensive investigation unveils intricate facets of HLADH’s catalytic mechanisms, providing a platform for further exploration in enzymology and biocatalysis.