 Dear students, in this topic we shall discuss the digestive enzymes for protein hydrolysis that is proteases. Proteases are proteolytic enzymes which digest proteins. They break the peptide bonds of the proteins and polypeptides. There are two types of proteases. One are the endopeptidases and second are exopeptidases. The endopeptidases are the proteolytic enzymes which attack the peptide bonds within protein molecule. They break the larger peptide chains into shorter polypeptide segments. Exopeptidases attack the terminal peptide bonds of shorter polypeptides. As a result, they release either the free amino acids or break larger polypeptides into dipeptides or tripeptides. Dear students, proteases have specificity in their action. Their specificity to attack peptide bonds formed by particular amino acids is observable in many of famous digestive tract proteases. For example, trypsin attacks the peptide bonds formed by arginine or lysine. This is a tripsin which attacks the peptide bonds of such parts where arginine or lysine is formed. This arginine or lysine bond is deep within the protein molecule. This is a chymotrypsin which attacks peptide bonds which are formed by amino acids, tyrosine, phenylalanine, tryptophan, leucine, and methionine. This is a chymotrypsin which acts as a specific for breaking these peptide bonds. Dear students, now we shall take few examples of proteases secreted in digestive juices of digestive tract. First we shall discuss papcine. Papcine is secreted in the gastric juice in stomach. It is the enzyme which begins protein digestion. It functions best in acidic pH ranging in between 1 and 2. This acidic pH is maintained by gastric hydrochloric acid. Papcine hydrolyzes proteins into polypeptides and few free amino acids. Many proteases are also secreted in pancreatic juice. For example, chymotrypsin, chymotrypsin, and carboxypeptidase. These enzymes yield a mixture of free amino acids and small peptide chains. Dear students, small intestine also produces some peptidases. These proteases are secreted by the epithelium. The most famous of these is the erypsine which acts on polypeptides and hydrolyzes them into shorter oligo peptides which contain 2 to 3 amino acid residues and then in the second step further breaks them into individual amino acids.