Question

Ligases is a class of enzymes responsible for catalysing the linking together of two compounds.Which of the following bonds is not catalysed by it?

• A. C-C
• B. P-O
• C. C-O
• D. C-N

Answer 1

The Correct Option is A

The question pertains to the class of enzymes known as ligases. These enzymes are responsible for catalyzing the joining of two molecules by forming a new chemical bond. Ligases typically work by catalyzing the joining of carbon-oxygen (C-O), phosphorous-oxygen (P-O), and carbon-nitrogen (C-N) bonds.

Let's evaluate each option provided in the context of ligase activity:

• C-C (Carbon-Carbon) Bonds: Ligases are generally not responsible for catalyzing the formation of carbon-carbon bonds. This type of bond formation is more commonly associated with enzymes in the lyase class, specifically synthases, which differ from ligases.
• P-O (Phosphorous-Oxygen) Bonds: Ligases are known to participate in catalyzing the formation of phosphorous-oxygen bonds. An example is the catalysis of ATP-dependent reactions where phosphate groups are transferred, creating P-O bonds.
• C-O (Carbon-Oxygen) Bonds: Ligases can also catalyze the formation of carbon-oxygen bonds. An example would be the joining of a molecule with an alcohol or carboxylic group, forming an ester or similar linkage.
• C-N (Carbon-Nitrogen) Bonds: Ligases are capable of catalyzing the formation of carbon-nitrogen bonds. Examples include reactions that form peptide bonds between amino acids, often facilitated by peptide ligases or synthetases.

Based on this analysis, the correct answer is that ligases do not catalyze the formation of C-C (Carbon-Carbon) bonds.