Transition State and Catalysis The transition state and catalysis are central concepts in enzyme action and enzymatic reactions. Understanding how enzymes stabilize the transition state and lower activation energy is key to explaining how enzymes accelerate biochemical reactions. What is the Transition State? The transition state refers to a high-energy, unstable intermediate state during a … Read more
Induced Fit Hypothesis The Induced Fit Hypothesis is a more refined model of enzyme-substrate interaction than the older Lock-and-Key Model. It was proposed by Daniel Koshland in 1958 to explain the flexibility and dynamic nature of enzymes during the enzyme-substrate binding process. According to this hypothesis, the enzyme’s active site is not a rigid, perfectly … Read more
Lock-and-Key Model of Enzyme Action The Lock-and-Key Model is one of the earliest and simplest theories proposed to explain the mechanism of enzyme action. It was introduced by Emil Fischer in 1894, and it suggests that the enzyme and its substrate fit together in a manner similar to a key fitting into a lock. This … Read more
Enzyme-Substrate Complex Formation The enzyme-substrate complex (ES complex) is the fundamental interaction that drives enzyme catalysis. This complex is formed when the enzyme binds to its specific substrate(s), which are the molecules upon which the enzyme acts. The formation of the enzyme-substrate complex is essential for the enzyme to perform its catalytic function and convert … Read more
Mechanisms of Enzyme Action Enzymes function as biological catalysts, increasing the rate of biochemical reactions by lowering the activation energy required for a reaction to occur. They achieve this by providing an alternative reaction pathway with a lower energy barrier. The mechanism by which enzymes achieve this is intricate and involves multiple steps, which can … Read more
Ligases (EC 6) Ligases are enzymes classified under EC 6 that catalyze the joining of two molecules by forming new covalent bonds, often accompanied by the hydrolysis of a high-energy molecule like ATP or GTP. These enzymes are crucial in a variety of biological processes, including DNA replication, repair, and biosynthesis of macromolecules such as … Read more
Isomerases (EC 5) Isomerases are enzymes classified under EC 5 that catalyze the rearrangement of atoms within a molecule, converting it into its isomeric form. Isomerases play crucial roles in many metabolic pathways by facilitating the conversion of molecules into different structural or stereoisomers without changing the molecular formula. These enzymes are essential for maintaining … Read more
Lyases (EC 4) Lyases are enzymes classified under EC 4 that catalyze non-hydrolytic reactions in which a functional group is removed from a substrate or added to a substrate without the use of water or oxidation. Unlike hydrolases, which break bonds by using water, lyases break or form bonds by mechanisms that do not involve … Read more
Hydrolases (EC 3) Hydrolases are enzymes classified under EC 3 that catalyze the hydrolysis of chemical bonds. Hydrolysis is a reaction in which a water molecule is used to break a bond in a substrate, resulting in the formation of two products. Hydrolases are involved in many essential biological processes, including digestion, cellular metabolism, and … Read more
Transferases (EC 2) Transferases are enzymes classified under EC 2 that catalyze the transfer of functional groups (such as methyl, acetyl, amino, phosphate, or sugar groups) from one molecule (the donor) to another molecule (the acceptor). These enzymes play crucial roles in various metabolic processes, including protein modification, signal transduction, and the regulation of cellular … Read more