Question

How would base pairing in DNA be affected if the bases existed in the enol and imine form?

I don't understand the question, could you give a simple example thanks

Answer 1

In DNA, H- atoms usually prefer specific atomic location in purine and pyrimidine bases .

The N- atoms attached to C , G and A are in the amino form ( - NH2 )

The O- atom in G and T are in Keto form ( = O )

Keto (C=O) enol (C-OH)

Amino- (NH2) imino (=NH)

(base pairing rules are reversed)

A(amino) = C * (imino) AC base pairs

A *(imino) = C (amino)

G (keto) ≡ T * (enol ) GT base pairs

G * (enol) ≡ T (keto)

Rare tautomers of DNA bases can cause mispairing

Normal base pairing in DNA is A-T and G-C. The tautomers forms are capable of unusual base pairing like T-G and C-A.