Better Peptides via Chemical Glycosylation: Somatostatin Analogues Having a Human Complex-Type N-Glycan with Improved Drug Properties.

Somatostatin (somatotropin release-inhibiting factor, SRIF) is a growth hormone inhibitory factor in the form of a 14- or 28-amino acid peptide. SRIF affects several physiological functions through its action on five distinct SRIF receptor subtypes (sst1-5). Native SRIF has only limited clinical applications due to its rapid degradation in plasma. To overcome this obstacle, we have developed glycosylated SRIF analogues that possess not only metabolic stability but also high affinity to all five receptor subtypes by attaching human complex-type oligosaccharides. Such glycosylated SRIF analogues with improved pharmacokinetic profiles could be potent and novel therapeutic drugs for SRIF-related diseases in which several SRIF receptor subtypes are closely involved, and also shed light on new indications. Our results show that chemical glycosylation can be a powerful tool for the development of peptide and protein analogues superior to the original molecules with enhanced drug properties.