Biochemistry Questions / Discuss the difference between the associative and dissociative mechanisms in nuclease enzymes, and explain how the nature of R groups influences their occurrence. Provide examples to support your explanation.

Associative mechanisms involve the leaving group being lost before the nucleophile attacks. Dissociative mechanisms involve the nucleophile being added as the leaving group leaves.

The probability of whether an associative or dissociative mechanism is used depends on what R group is present. Nucleic acids favour the associative mechanism.