Structure and activity of HYI killer toxin from Hansenula saturnus

The primary structure of HYI killer toxin produced by Hansenula saturnus was determined in its reduced and pyridylethylated form, as well as the peptides resulting from protease digestion. It was found that the HYI killer toxin consisted of 87 amino acid residues and the molecular weight was calculated to be 9543 Da. It showed 87% homology with HM-1 killer toxin produced by H. mrakii, while there were multiple mutations including one amino acid deletion which, nevertheless, did not alter the strong cytocidal effect on sensitive yeasts.