Novel glycosylated VIP analogs: synthesis, biological activity, and metabolic stability.
Vasoactive intestinal peptide (VIP) is a prominent neuropeptide, exhibiting a wide spectrum of biological activities in mammals. However, the clinical applications of VIP are mainly hampered because of its rapid degradation in vivo. Peptide glycosylation, a procedure frequently used to increase peptide resistance to proteolytic degradation and consequently increase peptide metabolic stability, has not been performed yet on VIP. The presence of three N-glycosylation sites on VIP receptor type 1 (VPAC1) was previously demonstrated. Therefore, glycosylation of the VIP ligand could potentially increase its receptor affinity because of glyco-glyco interactions between the ligand and the receptor. In order to enhance VIP's metabolic stability and to increase its ligand-receptor binding/activation, eight glycosylated VIP derivatives were successfully synthesized by the solid-phase procedure. Each VIP analog was monoglycosylated by a monosaccharide addition to one amino-acid residue along the sequence. Glycosylation did not affect the alpha-helical structure shown by the native VIP in organic environment. Few glycosylated VIP analogs displayed highly potent VPAC1 receptor binding and cAMP-induced activation; only 4-6 fold lower in comparison to the native VIP. Furthermore, the peptide analog glycosylated on Thr11 ([11Glyc]VIP) showed a significantly enhanced stability toward trypsin enzymatic degradation in comparison to VIP. Analysis of the degradation products of [11Glyc]VIP showed that differently from VIP, incubation of the peptide [11Glyc]VIP with trypsin resulted in no cleavage at the Arg12-Leu13 peptide bond, suggesting that VIP glycosylation may lead to enhanced metabolic stability.
Dangoor
David
D
Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
Biondi
Barbara
B
Gobbo
Marina
M
Vachutinski
Yelena
Y
Fridkin
Mati
M
Gozes
Illana
I
Rocchi
Raniero
R
D006031:Glycosylation; D011485:Protein Binding; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I / Q000502:physiology; D013329:Structure-Activity Relationship; D014660:Vasoactive Intestinal Peptide / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*
D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D014660:Vasoactive Intestinal Peptide