Historically, the first universal base employed was 2’-deoxyInosine (dI). DeoxyInosine is a naturally occurring base that, while not truly universal, is less destabilizing than mismatches involving the four standard bases. Hydrogen bond interactions between dI and dA, dG, dC and…

DeoxyUridine (dU) can be substituted for dT in DNA oligonucleotides. The base can be removed by the enzyme uracil-Ndeglycosylase (UNG), which renders the oligo susceptible to strand scission. One common use of this strategy is to eliminate amplifi ed DNA and prevent cross-contamination. ChEBI:…