PURIFICATION AND ANALYSIS OF PLASMATIC COMPONENTS OF MIDDLE MOLECULAR-WEIGHT IN PATIENTS WITH UREMIC SYNDROME

Many hormonal, metabolic and enzymatic alterations have been described in patients with chronic renal failure (CRF) after prolonged hemodial ysis treatment. This toxicity has been associated with the accumulatio n of middle molecular weight components, called 'middle molecules', in their blood. To investigate the chemical nature of these molecules, 2 0 CRF patients were studied and compared with 10 control subjects. Ser a from these individuals were treated with molecular exclusion chromat ography, the components of high molecular weight were eliminated from the elution peaks, and the remainder was then concentrated by lyophili zation. The zones of greatest concentration were fractioned by ionic e xchange chromatography and by HPLC in reverse phase. Infrared spectros copy was also performed on the most relevant zones, as well as SDS/PAG E. Finally, the amino acid sequence of a peak presenting the best cond itions was analyzed. The results indicate that the majority of the com pounds isolated are peptides, amino acids or amino alcohols, and that many of these 'middle molecules' are joined to trace metals.