Amylase is an enzyme that catalyzes the hydrolysis of starch, a polysaccharide composed of glucose units, into smaller oligosaccharides and eventually maltose, a disaccharide composed of two glucose molecules. The enzyme catalytic mechanism of amylase involves several steps, which ultimately lead to the breakdown of starch in the human digestive system.1. Binding of substrate: The first step in the catalytic mechanism of amylase is the binding of the starch molecule to the active site of the enzyme. The active site contains several amino acid residues that interact with the substrate, stabilizing it and positioning it for catalysis.2. Catalytic cleavage: Amylase catalyzes the hydrolysis of the glycosidic bond between glucose units in the starch molecule. This is achieved through a two-step process involving a nucleophilic attack and the transfer of a proton. In the first step, a negatively charged oxygen atom from a water molecule attacks the electrophilic carbon atom of the glycosidic bond. This is facilitated by a catalytic residue in the active site, usually a glutamate or aspartate, which acts as a general acid to donate a proton to the leaving group the oxygen atom of the adjacent glucose unit . In the second step, the same catalytic residue acts as a general base, abstracting a proton from the water molecule, which leads to the formation of a new glycosidic bond and the release of maltose or an oligosaccharide.3. Product release: After the hydrolysis reaction is complete, the maltose or oligosaccharide product is released from the active site of the enzyme. This allows another starch molecule to bind to the enzyme and undergo hydrolysis, continuing the catalytic process.In the human digestive system, the breakdown of starch begins in the mouth, where salivary amylase is secreted by the salivary glands. As the food is chewed and mixed with saliva, the amylase starts to break down the starch into smaller oligosaccharides. The process continues in the small intestine, where pancreatic amylase is secreted and further hydrolyzes the starch into maltose and other small oligosaccharides. These smaller carbohydrates are then broken down into individual glucose units by other enzymes, such as maltase and isomaltase, which are absorbed by the intestinal cells and used for energy production or storage.