Patent ID: 8710008

Claim:
A peptide comprising a unit of formula (II) wherein each X is independently a C 1-6 alkyl or C 2-6 alkenyl group, or the two X groups taken together form a covalent or non-covalent link between the two O groups, which is a C 1-10 saturated or unsaturated carbon chain optionally interrupted by one or more heteroatoms selected from O, S, N, P, or Si, or one X represents an azido group and the other an C 2-6 -alkynyl group; each Y is independently C, CH, CH 2 , N or NH; R 1 is H or C 1-6 alkyl; R 2 is H or C 1-6 alkyl; R 5 is a C 1-6 alkyl group; R 3 and R 4 are protective groups for carboxylic groups or amino groups respectively, fluorescent probes, radiolabeled groups or a further peptide chain with 1-20 amino acids in the chain, the end groups of which optionally carry protective groups for carboxylic groups or amino groups respectively, fluorescent probes, or radiolabeled groups; or a salt of the peptide.