Purification of a Toxic Phytohæmagglutinin from Black Beans (Phaseolus vulgaris)

Abstract

BEANS, like other seeds of the Leguminosae, contain some proteins of remarkable biological activity. For many years a bean phytohæmagglutinin has been known^1,2. Rigas and Osgood³ recently described two different factors with hæmagglutinating properties. Other authors^4,5 have observed toxic effects in animals fed with raw beans or with certain preparations obtained by extracting bean meal. The hæmagglutinin factors prepared according to the original method³ do not seem to be responsible for the toxic effect of raw beans, as they have only slightly toxic properties. Experiments carried out by one of us (W. J.) have also established the toxicity of beans that cannot be ascribed to the trypsin inhibitor (another protein) described by Bowman⁶. We therefore undertook to isolate the toxic components of beans in order to obtain further information about their properties.