A spacer C3 moiety, when incorporated into an oligonucleotide, mimics the three carbon spacing between the 3’ and 5’ hydroxyls of the sugar unit. Although useful where the base at a specific site is unknown, the flexibility of the alkyl chain distorts the sugar-phosphate backbone. This can be alleviated an abasic spacer since incorporation of this modifier sits directly into the natural sugar-phosphate backbone with no adverse effect. This modifier mimics abasic sites and is useful in the study of mutations resulting from depurination.