Presence of activators
Presence of certain inorganic ions increases the activity of enzymes. The best examples are chloride ions activated salivary amylase and calcium activated lipases.
Effect of Inhibitors
The catalytic enzymatic reaction may be inhibited by substances which prevent the formation of a normal enzyme-substrate complex. The level of inhibition then depends entirely upon the relative concentrations of the true substrate and the inhibitor. Such inhibition, which depends on competition with the substrate for the active sites of the enzyme, is termed competitive inhibition. In other cases, the inhibitor combines with the enzyme-substrate complex to give an inactive enzyme-substrate-inhibitor complex, which cannot undergo further reaction to give the usual product. This is termed uncompetitive inhibition. Non competitive inhibition involves combination of the in hibitor with the enzyme or the enzyme substrate complex, to give inactive complexes. In this case, the inhibitor binds to sites, on the enzyme other than enzyme sites, resulting in deformation of the enzyme molecule so that the formation of the enzymesubstrate complex is slower than normal. Some enzymes undergo irreversible inactivation; reaction of the inhibitor with a functional group of the enzyme, resulting in a loss of its catalytic activity. Enzyme inhibitor plays a vital role in clinical utility and is listed in table 8.2.
Intext Quections
1. At optimal substrate concentration the rate of an enzymatic reaction or velocity (V) is directly proportional to the ………………
2. Velocity of ……………… increases with temperature of the medium.
3. The optimum pH of alkaline phosphatase are ………………
4. Allopurinol are ……………… inhibitor and used for treatment of ……….……..
