Molecular weight measurement of human satietin

Attempts were made to estimate the actual molecular weight of satietin, an endogenous food intake inhibitor, by means of classical and high-performance gel filtration and gel electrophoresis. Satietin, which proved to be a glycoprotein, was isolated from human plasma. Sephacryl S-300 gel and TSK-GEL G 3000 SW columns were used as media for gel filtration and gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE), respectively. A relatively good correlation was established between the molecular weight measurements carried out by different methods, although satietin as a carbohydrate-rich glycoprotein gave an underestimated value by gel filtration when the calibration graphs were constructed with simple proteins. The molecular weight of satietin was determined to be about 43,000 daltons by SDS-PAGE and 29,000 daltons by gel filtration when using a buffer containing 1% of sodium dodecyl sulphate.