 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 the famous digestive tract proteases. For example, trypsin attacks the peptide bonds formed by arginine or lysine. This trypsin attacks on the parts of the protein molecule where peptide bonds are made by arginine or lysine. This trypsin attacks peptide bonds formed by amino acids tyrosine, phenylalanine, tryptophan, leucine and methionine. In amino acids k elawa banae hui peptide bonds par chymotrypsin act nahi kati. It means it is 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 papsin. Papsin is secreted in the gastric juice in stomach. It is the enzyme which begins protein digestion. It functions past in acidic pH ranging in between 1 and 2. This acidic pH is maintained by gastric hydrochloric acid. Papsin hydrolyzes proteins into polypeptides and few free amino acids. Many proteases are also secreted in pancreatic juice. For example, trypsin, chymotrypsin and carboxypeptides. These enzymes yield a mixture of free amino acids and small peptide chains. Small intestine also produces some peptidases. These proteases are secreted by the epithelium. And the most famous of these is the erypsin 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.