Abstract
By applying a preliminary treatment with non-polar resin (XAD-4) adsorption after ultrafiltration (1 KD) and a ‘hydrophobic’ HPLC system, nine of middle molecular sub-stances containing amino acids were isolated from hemofiltrates of a dialysis patient. To characterize uremic middle molecules, these substances were examined as follows: (1)the adsorption spectra (200-400 am), (2) the hydrophobicity in comparison with biologically active peptides, (3) the amino acid proportion and the detection of non-amino acid compo-nents, (4) the dansylation and the enzymatic hydrolysis. The results indicated that the spectral pattern and the hydrophobicity of these substances were dependent on structural features of non-amino acid components. And it was also clarified that the dansylation of amino acid residues in the molecules and the enzymatic hydrolysis of them were hard. This hardly digestible character in itself may lead to the retention of these middle mol-ecular substances in blood circulation of patient.
