 However, later research showed that triple-stranded, quadruple-stranded and other more complex DNA molecular structures required Hoogsteen base pairing.The entire field of synthetic biology began with work by researchers such as Erik T. Kool, in which bases other than A, C, T and G are used in a synthetic DNA.In addition to synthetic DNA there are also attempts to construct synthetic codons, synthetic endonucleases, synthetic proteins and synthetic zinc fingers.