Enzymes are essential macro-molecules. They play vital roles in maintenance of life by catalyzing biological reactions. Comprehending the link between enzyme motions (dynamics) and their function is important in designing new therapeutic drugs, inhibitors and engineered enzymes with novel functionalities. Changing the local structure (mutation) or the mass of these macro-molecules lead to perturbation of dynamics. My thesis focuses on identifying the effects of altered dynamics on enzyme activity which are either mutated or mass-modulated.