Chemo-enzymatic synthesis of the glycosylated α-mating factor of Saccharomyces cerevisiae and analysis of its biological activity

The effect of glycosylation on a bioactive peptide was studied using yeast Saccharomyces cerevisiae α-mating factor, which is composed of 13 amino acids. In this study, we prepared glycosylated α-mating factor by chemo-enzymatic synthesis. At first, N-acetylglucosaminyl α-mating factor (Trp–His–Trp–Leu–Gln(GlcNAc)–Leu–Lys–Pro–Gly–Gln–Pro–Met–Tyr) was chemically synthesized by the solid-phase method. Then, using the transglycosylation activity of Mucor hiemalis endo-β-N-acetylglucosaminidase, we synthesized glycosylated α-mating factor with a glutamine-linked sialo complex type oligosaccharide. The biological activity of α-mating factor derivatives was examined by means of a growth arrest assay using secreted-protease-defective a cells of S. cerevisiae. The results showed that the bioactivity of glycosylated α-mating factor was lower than that of native α-mating factor. However, when sialic acid was removed from the complex type sugar chain of glycosylated α-mating factor, its bioactivity was recovered. Glycosylated α-mating factor exhibited higher resistance against proteolysis than native α-mating factor. It was found that the bioactivity of N-acetylglucosaminyl α-mating factor was higher than that of α-mating factor. Circular dichroism studies indicated that a slight change in the structure of α-mating factor may influence its activity.