title: [Endonuclease activity of recombinant pancreatic nuclease (A-K7H)].
abstract: Pancreatic ribonuclease A (RNase A) is a endonuclease that catalyzes depolymerization of ribonucleic acid (RNA) releasing oligonucleotides. In the process of binding enzyme with substrate are involved several non-catalytic phosphate binding subsites, one of them is p2, additional to main catalytic site p1. RNaza A prefers binding and cleavage of longer substrate molecules, and 3',5'-phosphodiester bond should be some six-seven residues apart from the end of molecules of the chain of RNA. In this work is analysed endonuclease activity of recombinant pancreatic RNase A (K7H), that in position seven instead of a lysine there is a histidine, amino acid residue that participates in main catalytic site p1. Mutant enzyme is obtained by site-directed mutagenesis by Kunkel. Results of this investigation have shown that substitution of lysine by histidine in position seven of RNase A has produced total deletion of p2 subsite, and K7H has lost endonuclease activity, and has become exonuclease. These results confirm central role of Lys-7 in establishing p2 subsite and endonuclease activity of pancreatic RNase A.
authors.affiliation: Zavod za fiziologiju, Medicinski fakultet Tuzla, Univerzitet Tuzla.
authors.forename: F
authors.initials: F
authors.lastname: Ljuca
authors.forename: M
authors.initials: M
authors.lastname: Moussaoui
authors.forename: E
authors.initials: E
authors.lastname: Boix
authors.forename: V
authors.initials: V
authors.lastname: Nogues
authors.forename: D
authors.initials: D
authors.lastname: Ljuca
authors.forename: C M
authors.initials: CM
authors.lastname: Cuchillo
mesh_terms: D019943:Amino Acid Substitution; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000737:chemistry; D012259:Ribonuclease, Pancreatic / Q000737:chemistry*
chemical_list: D011994:Recombinant Proteins; D012259:Ribonuclease, Pancreatic
vernacular_title: Endonukleazna aktivnost rekombinantne pankreasne ribonukleaze A-K7H.