Mechanism of Enzyme Action
The action of enzymes is to lower the activation energy or threshold of their substrates which. Therefore become activated and react with the other reactants .The specific amino acid sequence and molecular shape of the enzyme are of primary importance in this function but its mechanism is not yet properly under stood ,The main views have been expressed t explain this mechanism .
1. Lock and key or Template Hypothesis: Emil Fischer 1894 hypothesized that each enzyme molecule has a specific and rigid active site upon its surface .A reactant molecule having a matching geometrical configuration only can fit into this active site of enzyme like a key fitting into a lock forming an unstable enzyme substrate complex ,This linkage actives the substrate molecules to react readily with the other reactant of the reaction
2. Induced fit Model Hypothesis: The lock and key model has been modified by koshland 1971 and his co-workers who have suggested that the active silt of an enzyme molecule is flexible. As the specific substrate molecule links with the enzyme molecule the latter undergoes conformation changes so that the fit is improved the reactive groups of enzyme molecule move to their proper sites.