Enhancement of bioactivity of Saccharomyces cerevisiae α-mating factor by attachment of sugar moiety to glutamine residue

We prepared yeast Saccharomyces cerevisiae α-mating factor, a 13-amino acid pheromone produced by haploid α-cells, bound with glucose or N-acetylglucosamine at the fifth glutamine residue from the N-terminal by the chemical method of peptide synthesis. It was found that the bioactivity of glucosyl α-mating factor was higher than that of native α-mating factor. However, it was slightly lower than that of N-acetylglucosaminyl α-mating factor. This suggested that the N-acetylamino residue might play some important role in the enhancement of the bioactivity of α-mating factor. However, CD spectra analysis of α-mating factor and its derivatives demonstrated that their structures were almost identical. On the other hand, we attached a sialo complex type oligosaccharide to N-acetylglucosamine or its glucose residue by means of the transglycosylation activity of endo-β- N-acetylglucosaminidase from Mucor hiemalis (Endo-M). The attachment of the oligosaccharide to both α-mating factors reduced their activities. However, enzymatical trimming of the sialo complex type oligosaccharide recovered its activity.