Question

The transition state structure of the substrate formed during an enzyme reaction is:\
A. Permanent and stable
B. Transient but stable
C. Permanent but unstable
D. Transient and unstable

Answer 1

Hint: Enzymes are biological catalysts that can accelerate chemical reactions. Enzymes are made up of proteins and are also called biocatalysts. The enzymes are known to lower down the activation energy of a chemical reaction.

Complete answer: Enzymes are globular proteins which act as a catalyst in a chemical reaction.
-Enzymes accelerate the chemical reactions by lowering their activation energy which in turn the speech of the reaction.
-Enzymes have activation sites where they bind with the substrate through an induced fit model, also known as the lock and key model, to form an enzyme-substrate complex that is highly transient and unstable and readily converts into final products.
-Upon completion of the reaction the enzymes get back to their original state.
-Activation energy for an uncatalyzed reaction is generally higher than a catalyzed reaction.
Hence, the correct answer is Option D, i.e., Transient and unstable.

Note: Enzymes are proteins composed of sequences of amino acids that determine their structure and catalytic activity. The number of amino acid residues in the structure of an enzyme range from 62 to 2500 amino acid residues. However, during a chemical reaction merely 2-4 amino acids are directly involved. Enzymes themselves do not affect the equilibrium or Gibbs free energy of the reaction. They instead stabilize the transition state which in turn lowers down the activation energy for the reaction to take place and hence, speeds up the reaction.