Inhibition of Yadh
Inhibition of YADH
Aim
The aim of the experiment is to investigate the inhibitory effects of acetaldehyde.
Principle:
According to Palmer (1991), “an inhibitor is a substance decreases the rate of an enzyme catalysed reaction”. The binding of inhibitors normally affects the activity of an enzyme. Enzyme inhibition studies are important because most poisons and drugs achieve their effects by inhibiting cell. Enzyme inhibition is also an important phenomenon in the cell metabolism because allows for regulation in many cascade reactions in the cell (Seager, & Slabaugh, 2011). Enzymes are broadly classified into reversible and irreversible enzymes. The characteristic distinguishing feature of the two classes is that reversible inhibitors can be isolated from the enzymes by dialysis while irreversible inhibitors cannot. It can also be noted that reversible inhibitors form an equilibrium with the enzyme that last remains constant for a period of time while in irreversible inhibition the inhibitor increases during the same period.
There are two types of reversible inhibition namely competitive and non-competitive inhibition. A competitive inhibitor binds to the active site of the enzyme and thus competes with the substrate for the active site. They are able to do this because they have a similar structure to that of the enzyme. Once the enzyme is bound to the enzyme know further reaction can take place until it dissociates from the molecule hence it is often termed a dead end complex (Palmer, 1991). A classic example is the competitive inhibition of succinate dehydrogenase by malonate, succinate dehydrogenase catalyses the oxidation of succinate to fumarate. Another example is the inhibition of sulphur drugs that inhibit the synthesis of sulphur drugs. Competitive inhibition for enzymes that have a single substrate and single binding site can be shown by the following equations:
E + S ES E + P
EI equation 1……. (Palmer, 1991)
Competitive inhibition can
Aim
The aim of the experiment is to investigate the inhibitory effects of acetaldehyde.
Principle:
According to Palmer (1991), “an inhibitor is a substance decreases the rate of an enzyme catalysed reaction”. The binding of inhibitors normally affects the activity of an enzyme. Enzyme inhibition studies are important because most poisons and drugs achieve their effects by inhibiting cell. Enzyme inhibition is also an important phenomenon in the cell metabolism because allows for regulation in many cascade reactions in the cell (Seager, & Slabaugh, 2011). Enzymes are broadly classified into reversible and irreversible enzymes. The characteristic distinguishing feature of the two classes is that reversible inhibitors can be isolated from the enzymes by dialysis while irreversible inhibitors cannot. It can also be noted that reversible inhibitors form an equilibrium with the enzyme that last remains constant for a period of time while in irreversible inhibition the inhibitor increases during the same period.
There are two types of reversible inhibition namely competitive and non-competitive inhibition. A competitive inhibitor binds to the active site of the enzyme and thus competes with the substrate for the active site. They are able to do this because they have a similar structure to that of the enzyme. Once the enzyme is bound to the enzyme know further reaction can take place until it dissociates from the molecule hence it is often termed a dead end complex (Palmer, 1991). A classic example is the competitive inhibition of succinate dehydrogenase by malonate, succinate dehydrogenase catalyses the oxidation of succinate to fumarate. Another example is the inhibition of sulphur drugs that inhibit the synthesis of sulphur drugs. Competitive inhibition for enzymes that have a single substrate and single binding site can be shown by the following equations:
E + S ES E + P
EI equation 1……. (Palmer, 1991)
Competitive inhibition can
References: Cornish-Bowden A, (1995) Fundamentals of enzyme kinetics, Portland press, UK, pp. 93-106 Gerald K., (2010) Cell and Molecular biology: Concepts and experiments, Willey and Sons, USA, 6th edition, pp. 102-103 Seager S.L. & Slabaugh M.R. (2011) Chemistry for today General, Organic and Biochemistry, Brooks/Cole Cengage learning, USA, pp. 621 Palmer T., (1991). Understanding enzymes, Ellis Horwood, New York, 3rd edition, pp 139-154