HUMAN NONSECRETORY RIBONUCLEASES .1. PURIFICATION, PEPTIDE-MAPPING AND LECTIN BLOTTING ANALYSIS OF THE KIDNEY, LIVER AND SPLEEN ENZYMES

Human non-secretory neutral ribonucleases (RNases) from kidney, liver and spleen have been purified and characterized. SDS-PAGE indicates th at all three RNases are highly purified and have apparent mol. wts of 17-18 kDa. Kinetic analysis indicates that all three RNases have a bro ad pH optimum centred around 6.5, and all three have substrate specifi cities with significant preference for RNA and poly(U) when compared t o poly(C), poly(A) and poly(G). All of the above data, as well as immu noblotting data using. three polyclonal antibodies (anti-human liver R Nase, anti-human pancreatic RNase, anti-human eosinophil-derived neuro toxin), indicate that the three proteins are highly purified and are n on-secretory RNases (IIN). Further characterization by cyanogen bromid e peptide mapping and extensive lectin blotting indicated no significa nt differences between the three human RNases. All three RNases appear to have very similar, if not identical, protein backbones and all thr ee are glycoproteins which are recognized by lectins with specificity for GlcNAc, Fuc and, to a lesser extent, with specificity for Galbeta( 1-4)GkNAc. No significant tissue-specific differences were found among the three human non-secretory RNases.