title: Ribonuclease activity and substrate preference of human eosinophil cationic protein (ECP).
abstract: The eosinophil cationic protein (ECP), a potent helminthotoxin with considerable neurotoxic activity, was recently shown to also have ribonucleolytic activity. In this work the substrate preference of ECP ribonuclease action was studied in detail. With single-stranded RNA or synthetic polyribonucleotide substrates ECP showed significant but low activity, 70- to 200-fold less than that of bovine RNase A. ECP hydrolyzed RNA more rapidly than it did any synthetic polynucleotide. Poly(U) was degraded more rapidly than poly(C), and poly(A) and double-stranded substrates were extremely resistant. Defined low molecular weight substrates in the form of the 16 dinucleoside phosphates (NpN') and uridine and cytidine 2',3'-cyclic phosphates were tested, and none showed hydrolysis by ECP at a significant rate. The results link ECP ribonucleolytic activity to the 'non-secretory' liver-type enzymes rather than to the 'secretory' pancreatic-type RNases.
authors.affiliation: Dipartimento di Chimica Organica e Biologica, Università di Napoli, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Sorrentino
authors.forename: D G
authors.initials: DG
authors.lastname: Glitz
mesh_terms: D001798:Blood Proteins / Q000378:metabolism*; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000201:enzymology*; D006801:Humans; D008099:Liver / Q000201:enzymology; D009498:Neurotoxins / Q000378:metabolism; D011131:Polyribonucleotides / Q000378:metabolism; D012313:RNA / Q000378:metabolism*; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D001798:Blood Proteins; D047091:Eosinophil Granule Proteins; D009498:Neurotoxins; D011131:Polyribonucleotides; D012313:RNA; D012260:Ribonucleases; D012259:Ribonuclease, Pancreatic