Application of monoclonal antibodies to the isolation and characterization of a killer toxin secreted by Hansenula mrakii.

A strain of yeast, Hansenula mrakii, secretes a toxin that kills sensitive yeasts, such as Saccharomyces cerevisiae Monoclonal antibodies raised against the toxin had both binding and neutralizing activities. The toxin in culture media was isolated by an affinity column of monoclonal antibody. The toxin is a basic polypeptide with an isoelectric point at pH 9.1, and devoid of mannosides. It is composed of 88 amino acid residues with a molecular size of 10 721 Da. The monoclonal antibodies could be applicable to the analysis of biologically active sites on the toxin, in an attempt to synthesize chemically a small peptide with killer activity and little immunogenicity.