| Type: | Active_site | Name: | Ribonuclease A, active site |
| Description: | Pancreatic ribonucleases (RNaseA) are pyrimidine-specific endonucleases found in high quantity in the pancreas of certain mammals and ofsome reptiles []. Specifically, the enzymes are involved in endonucleolyticcleavage of 3'-phosphomononucleotides and 3'-phosphooligonucleotides ending in C-P or U-P with 2',3'-cyclic phosphate intermediates. Ribonuclease canunwind the DNA helix by complexing with single-stranded DNA; the complex arises by an extended multi-site cation-anion interaction between lysineand arginine residues of the enzyme and phosphate groups of the nucleotides. Other proteins belonging to the pancreatic RNAse family include: bovineseminal vesicle and brain ribonucleases; kidney non-secretory ribonucleases []; liver-type ribonucleases []; angiogenin, which induces vascularisationof normal and malignant tissues; eosinophil cationic protein [], acytotoxin and helminthotoxin with ribonuclease activity; and frog liver ribonuclease and frog sialic acid-binding lectin.The sequence of pancreatic RNases contains four conserved disulphide bonds and three amino acid residues involved in the catalytic activity.Pancreatic ribonucleases () are pyrimidine-specific endonucleases present in high quantity in the pancreas of a number of mammalian taxa and of a few reptiles [, ]. As shown in the following schematic representation of the sequence of pancreatic RNases there are four conserved disulphide bonds and three amino acid residues involved in the catalytic activity.+---------------------------+ | +------------------|------+| | | | xxxxx#xxxxxxCxxxxxxC#xxxxxxxCxxCxxxCxxxxxCxxxxxCxxxxxxCxxx#xxx| **** | | | | +---+ |+----------------------------+ 'C': conserved cysteine involved in a disulphide bond.'#': active site residue. '*': position of the pattern.A number of other proteins belongs to the pancreatic RNAse family and these are listed below.Bovine seminal vesicle and bovine brain ribonucleases.The kidney non-secretory ribonucleases (also known as eosinophil-derived neurotoxin (EDN) []).Liver-type ribonucleases [].Angiogenin, which induces vascularization of normal and malignant tissues. It abolishes protein synthesis by specifically hydrolyzing cellular tRNAs.Eosinophil cationic protein (ECP) [], a cytotoxin and helminthotoxin with ribonuclease activity.Frog liver ribonuclease and frog sialic acid-binding lectin [].The signature pattern for these proteins includes five conserved residues: a cysteine involved in a disulphide bond, a lysine involved in the catalytic activity and three other residues important for substrate binding. | Short Name: | RNaseA_AS |
