Purification and characterization of a mitosis inhibiting epidermal peptide

The term ‘chalone’ was originally applied to a group of mitosis inhibitors assumed to be produced by the differentiating cells in a tissue and acting on the proliferating cells within the same tissue (Bullough, 1960). In addition to their mitosis inhibiting effect the putative chalones were assumed to have several other properties, some of which have been substantiated by experiments. Many of these characteristics and even the very existence of this type of growth inhibitors are, however, still debated. Since such inhibitors could potentially be very important it seemed necessary to purify and characterize them biochemically. In a previous report ( Isaksson-Forsen et al., 1981 ) we described the partial purification of an epidermal mitosis inhibitor. This paper describes the full purification and the amino acid composition of this epidermal mitosis inhibitor.