Human pancreatic ribonuclease presents higher endonucleolytic activity than ribonuclease A.
Analyzing the pattern of oligonucleotide formation induced by HP-RNase cleavage shows that the enzyme does not act randomly and follows a more endonucleolytic pattern when compared to RNase A. The enzyme prefers the binding and cleavage of longer substrate molecules, especially when the phosphodiester bond that is broken is 8-11 nucleotides away from at least one of the ends of the substrate molecule. This more endonucleolytic pattern is more appropriate for an enzyme with a regulatory role. Deleting two positive charges on the N-terminus (Arg4 and Lys6) modifies this pattern of external/internal phosphodiester bond cleavage preference, and produces a more exonucleolytic enzyme. These residues may reinforce the strength of a non-catalytic secondary phosphate binding (p2) or, alternatively, constitute a new non-catalytic phosphate binding subsite (p3).
Rodríguez
M
M
Laboratori d'Enginyeria de Proteïnes, Departament de Biologia, Facultat de Ciències, Universitat de Girona, Campus de Montilivi s/n, 17071 Girona, Spain.
Moussaoui
M
M
Benito
A
A
Cuchillo
C M
CM
Nogués
M V
MV
Vilanova
M
M
D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D003568:Cytidine Monophosphate / Q000737:chemistry / Q000378:metabolism; D004720:Endonucleases / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism; D011066:Poly C / Q000737:chemistry / Q000378:metabolism; D012259:Ribonuclease, Pancreatic / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
D010710:Phosphates; D011066:Poly C; D004720:Endonucleases; D012259:Ribonuclease, Pancreatic; D003568:Cytidine Monophosphate