Practice question

Partial digestion arises when conditions prevent all sites from being cleaved. Impure DNA containing proteins, salts, or residual phenol inhibits enzyme binding. Incorrect buffer pH, Mg2+ concentration, or suboptimal temperature reduces catalytic activity. Too little enzyme or too short incubation also leaves some sites uncut. Excess enzyme drives reaction toward completion and, beyond optimum, may cause star activity with nonspecific cutting, not partial patterns. Therefore excess enzyme does not cause incomplete cleavage but rather overdigestion, making it non-contributory to partial digestion.