DETERMINATION ON THE MOLECULAR-WEIGHT OF EXTRACELLULAR RIBONUCLEASE ISOENZYMES FROM ASPERGILLUS-NIGER IN CRUDE EXTRACTS BY THIN-LAYER GEL-FILTRATION AND POLYACRYLAMIDE-GEL ELECTROPHORESIS

The extracellular ribonucleases from aspergillus niger culture medium were fractionated according to their molecular weight by thin layer ge l filtration through Sephadex G100 superfine and the enzyme activity w as detected by a standard staining technique on a replica print paper. Another replica paper was laid onto the top of a polyacrylamide gel a nd the absorbed proteins were separated by electrophoresis. By compari ng the electrophoretic pattern with that of a control not subjected to gel filtration, the molecular weight of each isoenzyme in the crude e xtract could be determined. Gel electrophoresis however, is only used to establish the correspondence between the original electrophoretic p attern of the isoenzymes in the crude preparation and that detected on the replica print paper taken after the thin layer gel filtration run . There was good agreement between the values obtained for the crude a nd purified enzymes.