Melonate inhibits the growth of pathogenic bacteria by inhibiting the activity of [2023]
Lipase
Dinitrogenase
Succinic dehydrogenase
Amylase
(3)
In competitive inhibition, the inhibitor closely resembles the real substrate in its molecular structure and inhibits the activity of the enzyme. Due to its close structural similarity with the substrate, the inhibitor competes with substrate for the substrate binding site of enzymes. Consequently, the substrate cannot bind and as a result, the enzyme action declines.
Inhibition of succinic dehydrogenase by malonate is one example of competitive inhibition. Malonate closely resembles the substrate succinate in structure. Such competitive inhibitors are often used to inhibit the growth of pathogenic bacteria.
Given below are two statements:
Statement I: Low temperature preserves the enzyme in a temporarily inactive state whereas high temperature destroys enzymatic activity because proteins are denatured by heat.
Statement II: When the inhibitor closely resembles the substrate in its molecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor.
In the light of the above statements, choose the correct answer from the options given below: [2023]
Statement I is true but Statement II is false.
Statement I is false but Statement II is true.
Both Statement I and Statement II are true.
Both Statement I and Statement II are false.
Name the class of enzyme that usually catalyze the following reaction : [2025]
Where, G → a group other than hydrogen
S → a substrate
→ another substrate
Hydrolase
Lyase
Transferase
Ligase
(3)
Enzymes catalysing a transfer of G group, (other than hydrogen) between a pair of substrates, S and S’ are known as transferases.
• Ligases catalyse the linking together of 2 compounds such as C – O, C – S, C – N bonds etc
• Lyases catalyse removal of groups from substrates by mechanisms other than hydrolysis leaving double bonds
Hydrolases are enzymes that catalyse hydrolysis of ester, ether, peptide , glycosidic, C – C, C – halide or P – N bonds.
Which one of the following enzymes contains ‘Haem’ as the prosthetic group? [2025]
RuBisCo
Carbonic anhydrase
Succinate dehydrogenase
Catalase
(4)
In peroxidase and catalase, which catalyze the breakdown of hydrogen peroxide to water and oxygen, haem is the prosthetic group and it is part of the active site of the enzymes.
Zinc is the cofactor in enzyme carbonic anhydrase.
RuBisCo is the most abundant protein in whole of the biosphere.
Succinate is the substrate of enzyme succinic dehydrogenase.
The protein portion of an enzyme is called: [2025]
Cofactor
Coenzyme
Apoenzyme
Prosthetic group
(3)
There are number of cases in which non-protein constituents called co-factors are bound to the enzyme to make the enzyme catalytically active.
In these instances, the protein portion of the enzymes is called the apoenzyme.
Three kinds of co-factors are identified prosthetic groups, co-enzymes and metal ions. Prosthetic groups are organic compounds and they are tightly bound with apoenzyme. Co-enzymes are also organic compounds but their association with apoenzyme is only transient.
