Purification and Amino Acid Sequence of Mating Factor from Saccharomyces cerevisiae

Abstract

Mating factor is a peptide excreted into the culture fluid by α-mating type cells of Saccharomyces cerevisiae X-2180 1B. The purification of the mating factor was carried out by ion exchange chromatography on phosphocellulose and Amberlite IRC 50 columns, followed by gel filtration on a Sephadex LH 20 column. The factor thus prepared was a peptide composed of Lys₁, His₁ Trp₂ Gln₂ Pro₂ Gly₁ Met₁ Leu₂ and Tyr₁ and was able to induce morphological changes on a-mating type cells at a concentration of 5 pg/ml.

The amino acid sequence of the mating factor was determined by the manual Edman degradation method using intact mating factor and its thermolytic peptides. The C-terminalamino acid residue was determined by digesting the factor with carboxypeptidase A. The complete amino acid sequence of the mating factor was established to be as follows:

$$\text{Trp}-\text{His}-\text{Trp}-\text{Leu}-\text{Gln}-\text{Leu}-\text{Lys}-\text{Pro}-\text{Gly}-\text{Gln}-\text{Pro}-\text{Met}-\text{Tyr}\mathrm{.}$$