| abstract |
Protein derivatives of formula (1) nA-CO-N(R¹)CH₂-Z-R² (1) nwherein A-CO is the residue of a protein or peptide A-CO₂H (especially where -CO₂H is the C-terminal carboxyl group of the protein or peptide); R¹ is a hydrogen atom or an alkyl, aryl or aralkyl group; Z¹, which may be present or absent is a spacer group; R² is a group -C(OH)(R³)CH₂NHR⁴ or -C(R³)O (where R³ and R⁴ which may be the same or different, is each a hydrogen atom or an alkyl, aryl or aralkyl group); with the proviso that when A-CO is a residue of insulin, R¹ is other than a hydrogen atom; and the salts thereof. The compounds may be prepared by a condensation reaction,, especially in the presence of an enzyme capable of catalysing the formation of a peptide bond. The compounds may be used to form protein conjugates in which a group of interest such as another protein or peptide or an effector or reporter group is coupled to the protein through a -N(R¹)CH₂-Z¹-C(OH)(R³)CH₂N= or -N(R¹)CH₂Z¹-CH= group. |