Question

if you to monitor the activity of any of the serine proteases as they degrade protein, you would note that the serine protease does not cut all of the recognition sites in the substratebat once- the recognition sites in the surface of the subrate protein are the first to be cut. Explain

Answer 1

Answer:

Pancreatic exocrine secretions- enzymes: serine proteases (trypsinogen, chymotrypsinogen, subtilinases), These are inactive and become active in the duodenum and later involve in breaking down the polymer macro molecules such as proteins into simple monomers as amino acids by "hydrolysis".

The crucial component in the mechanism of serine protease enzyme catalysis as they bind with the substrate is the formation of catalytic traid (His 57, ser 195 and aspar 102). This catalytic traid have the capability to recognize the catalytic sites of the substrate polypeptide as these substrates are in complex tertiary structure forms due to folding. The significant serine proteases geometry is enable them to recognize the substrate cleavage sites and they characteristically bind at the transition state and finally declines the overall activation energy of the reaction and thereby enables the significant catalytic ability of the enzyme. These zymozens (serine proteases) are initially inactive in the pancreas. These are inactive precursors of the serine proteases synthesized in the pancreas, incase if they become active where they synthesized without recognizing the substrate site may leading to autolysis (self-digestion) of the enzyme. Further this self digestion due to premature activation of serine proteases result in acute pancreatitis.     

Activation of the proteases is prerequisite during the catalysis of the substrate polypeptide. Hydroxyl group of serine proteases acts as nucleophile and the substrate polypeptide will be exposed with active site thereby a scissile covalent bond is mixed with the enzyme active site result in the proteolysis.