The invention provides a nucleotide or nucleoside having a base attached to a detectable label via a cleavable linker, characterized in that the cleavable linker contains a moiety selected from the group comprising: Formula (I) (wherein X is selected from the group comprising O, S, NH and NQ wherein...http://www.google.co.uk/patents/US7795424?utm_source=gb-gplus-sharePatent US7795424 - Labelled nucleotides
