Non diffusible toxic polypeptides in uraemic sera: a new group of uraemic toxins.

The composition and toxicity of polypeptides prepared from normal and uraemic sera by the combination of Dowex and Sephadex column chromatography have been studied. Significant changes in composition associated with an increased toxicity and decreased diffusibility of peptides (Mwt, 1800--2500 D) isolated from uraemic sera were detected. Due to their moderate of high toxicity as well as their poor or non-diffusibility, these uraemic polypeptides are proposed to be regarded as a new group of uraemic toxins.