Chymotrypsin catalyzes the hydrolysis of peptide bond and is therefore categoriz

Question

Chymotrypsin catalyzes the hydrolysis of peptide bond and is therefore categorized as a. oxidoreductase transferase hydrolase lyase ligase The ability for an enzyme to pick out one particular substrate from the myriad of molecules floating around its environment is an example of. natural selection specificity high affinity processivity none of the above The highest point in a reaction coordinate diagram represents. an intermediate of the reaction pathway the reactants in an exergonic reaction the products in an endergonic reaction the transition state the overall delta G for the reaction How does a catalyst affect the overall delta G of an endergonic reaction? it has no effect the reaction becomes more endergonic the reaction has a delta G of zero the reaction becomes exergonic none of the above How does a catalyst increase the rate of a reaction? it makes the reaction more exergonic it increases the temperature of the reaction it allows reacting m

Explanation / Answer

Ans. 11. Correct option. C. Hydrolases

Class 1: Oxidoreductases: The enzymes catalyzing oxidoreduction through transfer of electron, hydrogen atom or oxygen atom belong to ‘Oxidoreductases’ class of enzymes. The substrate that donates hydrogen in the donor: acceptor pair is said to be ‘oxidized’.

Class 2: Transferases: The enzymes catalyzing the transfer of a functional group from donor to acceptor molecule belong to ‘Transferases’.

Class 3: Hydrolases: The enzymes catalyzing the hydrolytic cleavage of a chemical bond (C-C, C-N, C-O, amide, ester, peptide bond, etc.) are categorized as ‘Hydrolases’. These enzymes hydrolyze the chemical bond by transferring a specific group to a water molecule. Therefore, all hydrolases can also be regarded as transferases, but the reverse being not true. In principle, the specific transferases that catalyze the transfer of a functional group to water are called hydrolases.

Class 4: Lyases: The enzymes catalyzing non-oxidative, non-hydrolytic cleavage of a chemical bond (C-C, C-N, C-O, C-S, C-X, etc., where X= halide) are classified as ‘Lyases’. The enzyme catalyzes bond cleavage by elimination of two substituents in the substrate, thus the resultant product may show unsaturation or ring formation. In later catalytic steps, some lyases also add new groups to the points of elimination, thus the final product does not show unsaturation. -

Class 6: Ligases: The enzymes catalyzing the covalent linkage of two molecules by hydrolyzing ATP or other similar triphosphates.

Ans. 12. Correct option. B. specificity

The property of an enzyme to bind only to its substrate among the wide array of molecules in the reactions environment is called its specificity.

Natural selection is related to “evolution”, not to specificity in direct context.

High affinity indicates that a molecule binds to enzyme more strongly. This can be an inhibitor, or other substrate or the true substrate itself that may bind to the enzyme with high affinity when compared to other molecules. However, it is NOT equivalent to specificity. It is a relative term that denotes the binding affinity of two or more molecules to the same enzyme.

Processivity is the rate of catalysis. It is not equivalent to specificity.

Ans. 13. D. Transition state.

See a reaction energy diagram, the transition state (TS) is the highest point.

Reaction intermediates lie below TS in energy diagram.

All reactants and products also lie below “intermediates” as well as the TS.

Overall dG of the reaction is NOT a point, it’s the difference between energy of reactants and products.

Ans. 14. A. it has no effect.

Note that Overall dG of the reaction is the difference between energy of reactants and products. A catalyst does not affect this difference.

Since dG remains constant, the reaction can’t become more endergonic or dG can’t become zero or even can’t become exergonic.

Ans. 15. C. It allows………. Transition state.

Catalyst reduces activation energy of the reaction, so TS can form more easily.

Catalyst does not generate reactants, so it cannot increase reactant conetration.

A catalyst is a substance that increases the rate of reaction without getting consumed itself in due course of reaction. That is, the catalyst is regenerated at the end of reaction- with no net loss in the amount of catalysts added in the reaction.

A catalyst increases rate of reaction by reducing activation energy so that a relatively larger fraction of reactants attain sufficient energy to successively participate product formation. In presence of a catalyst, the activation energy of both forward and backward reaction decreases by same magnitude. Therefore, rate of reaction in both directions increase. It is also noteworthy that catalyst only increases the rate on reaction, but leaves the equilibrium unaffected.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.