Ribonuclease, abbreviated commonly as RNase, is a nuclease that catalyzes the hydrolysis of RNA into smaller components. A nuclease is an Enzyme capable of cleaving the Phosphodiester bonds between the nucleotide subunits of Nucleic acids Older papers may use terms such as Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst Hydrolysis is a Chemical reaction during which one or more water molecules are split into hydrogen and hydroxide ions which may go on to participate in further reactions Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units They can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within the EC 2. A Endoribonuclease is a Ribonuclease Endonuclease. Example includes both single proteins like RNase III, RNase A, RNase T1 and An exoribonuclease is an Exonuclease Ribonuclease, which are enzymes that degrade RNA by removing terminal Nucleotides from either the 7 (for the phosphorolytic enzymes) and 3. 1 (for the hydrolytic enzymes) classes of enzymes.

Contents 1 Function 2 Classification 2.1 Major types of endoribonucleases 2.2 Major types of exoribonucleases 3 External links 4 References

Function

RNases are extremely common, resulting in very short lifespans for any RNA that is not in a protected environment. One mechanism of protection is ribonuclease inhibitor (RI), which comprises a relatively large fraction of cellular protein (~0. Ribonuclease inhibitor (RI is a large (~450 residues ~49 kDa acidic (pI ~4 1%) and which binds to certain ribonucleases with the highest affinity of any protein-protein interaction; the dissociation constant for the RI-RNase A complex is ~20 fM under physiological conditions. Protein-protein interactions refer to the association of Protein molecules and the study of these associations from the perspective of Biochemistry, Signal transduction RI is used in most laboratories that study RNA to protect their samples against degradation from environmental RNases.

Similar to restriction enzymes, which cleave highly specific sequences of double-stranded DNA, a variety of endoribonucleases have been recently classified which recognize and cleave specific sequences of single-stranded RNA. A restriction enzyme (or restriction Endonuclease) is an Enzyme that cuts double-stranded DNA at specific recognition Nucleotide Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known A Endoribonuclease is a Ribonuclease Endonuclease. Example includes both single proteins like RNase III, RNase A, RNase T1 and

RNases play a critical role in many biological processes, including angiogenesis and self-incompatibility in flowering plants (angiosperms). Angiogenesis is a physiological process involving the growth of new Blood vessels from pre-existing vessels The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group Additionally, RNases in prokaryotic toxin-antitoxin systems are proposed to function as plasmid stability loci, and as stress-response elements when present on the chromosome.

Classification

Major types of endoribonucleases

• EC 3.1.27.5: RNase A is an RNase that is commonly used in research. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. Ribonuclease A (RNase A is an Endonuclease that cleaves single-stranded RNA. RNase A (e. g. , bovine pancreatic ribonuclease A: PDB 2AAS) is one of the hardiest enzymes in common laboratory usage; one method of isolating it is to boil a crude cellular extract until all enzymes other than RNase A are denatured. The Protein Data Bank ( PDB) is a repository for 3-D structural data of Proteins and Nucleic acids These data typically obtained by X-ray crystallography Denaturation is a process in which Proteins or Nucleic acids lose their structure (tertiary structure by application of some external stress or compound for It is sequence specific for single stranded RNAs. It cleaves 3'end of unpaired C and U residues, leaving a 3'-phosphorylated product.

• EC 3.1.26.4: RNase H is a ribonuclease that cleaves the RNA in a DNA/RNA duplex to produce ssDNA. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. The Enzyme RNase H ( is a Ribonuclease that cleaves the 3'-O-P-bond of RNA in a DNA/RNA Duplex to produce 3'-hydroxyl and 5'-phosphate terminated RNase H is a non-specific endonuclease and catalyzes the cleavage of RNA via a hydrolytic mechanism, aided by an enzyme-bound divalent metal ion. RNase H leaves a 5'-phosphorylated product.

• EC number 3. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. 1. ??: RNase I cleaves 3'-end of ssRNA at all dinucleotide bonds leaving a 5´ hydroxyl, 2',3'-cyclic monophosphate.

• EC 3.1.26.3: RNase III is a type of ribonuclease that cleaves rRNA (16s rRNA and 23s rRNA) from transcribed polycistronic RNA operon in prokaryotes. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. RNase III enzymes specifically bind to and cleave double-stranded RNA (dsRNA It also digests double strands RNA (dsRNS)-Dicer family of RNAse, cutting pre-miRNA (60-70bp long) at a specific site and transforming it in miRNA (22-30bp), that is actively involved in the regulation of transcription and mRNA life-time.

• EC number 3. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. 1. ??: RNase L is an interferon-induced nuclease which, upon activation, destroys all RNA within the cell

• EC 3.1.26.5: RNase P is a type of ribonuclease and is currently under heavy research. RNase L is an Interferon -induced Ribonuclease which upon activation destroys all RNA within the cell (both cellular and viral This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. Ribonuclease P (RNase P is a type of Ribonuclease that is currently under heavy research RNase P is unique from other RNases in that it is a ribozyme – a ribonucleic acid that acts as a catalyst in the same way that a protein based enzyme would. A ribozyme (from ribo nucleic acid en' zyme', also called RNA Enzyme or catalytic RNA is an RNA Molecule that catalyzes Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Its function is to cleave off an extra, or precursor, sequence of RNA on tRNA molecules. Transfer RNA (abbreviated tRNA) is a small RNA (usually about 74-95 nucleotides that transfers a specific Amino acid to a growing polypeptide chain at Further RNase P is one of two known multiple turnover ribozymes in nature (the other being the ribosome). Ribosomes ( from ribo nucleic acid and "Greek soma ( meaning body") are complexes of RNA and Protein that

• EC number 3. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. 1. ??: RNase PhyM is sequence specific for single stranded RNAs. RNase PhyM is a type of Endoribonuclease which is sequence specific for single stranded RNAs It cleaves 3'-end of unpaired A and U residues.

• EC 3.1.27.3: RNase T1 is sequence specific for single stranded RNAs. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. Ribonuclease T1 (sometimes abbreviated RNase T1) is a fungal Endonuclease that cleaves single-stranded RNA after Guanine residues It cleaves 3'-end of unpaired G residues.

• EC 3.1.27.1: RNase T2 is sequence specific for single stranded RNAs. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. It cleaves 3'-end of all 4 residues, but preferentially 3'-end of As.

• EC 3.1.27.4: RNase U2 is sequence specific for single stranded RNAs. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. It cleaves 3'-end of unpaired A residues.

• EC 3.1.27.8: RNase V1 is non-sequence specific for double stranded RNAs. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. It cleaves base-paired nucleotide residues.

• EC 3.1.27.8: RNase V

Major types of exoribonucleases

• EC number EC 2.7.7.8: Polynucleotide Phosphorylase (PNPase) functions both as an exonuclease as well as a nucleotidyltransferase. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. Polynucleotide Phosphorylase ( PNPase) is bifunctional Enzyme with a phosphorolytic 3' to 5' Exoribonuclease activity and a 3'-terminal Oligonucleotide Exonucleases are enzymes (found as individual enzymes or as parts of larger enzyme complexes that cleave Nucleotides one at a time from an end of a polynucleotide chain Nucleotidyltransferases are Phosphotransferase enzymes which act upon components of Nucleotides They are classified under EC number 2

• EC number EC 2.7.7.56: RNase PH functions both as an exonuclease as well as a nucleotidyltransferase. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. RNase PH is an 3'-5' Exoribonuclease and Nucleotidyltransferase, present in Archaea and Bacteria, that is involved in TRNA processing Exonucleases are enzymes (found as individual enzymes or as parts of larger enzyme complexes that cleave Nucleotides one at a time from an end of a polynucleotide chain Nucleotidyltransferases are Phosphotransferase enzymes which act upon components of Nucleotides They are classified under EC number 2

• EC number 3. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. 1. ??: RNase II is responsible for the processive 3'-to-5' degradation of single-stranded RNA. Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units

• EC number 3. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. 1. ??: RNase R is a close homolog of RNase II, but it can, unlike RNase II, degrade RNA with secondary structures without help of accessory factors. RNase R is an 3'-5' Exoribonuclease closely related to RNase II, which has been shown to be involved in MRNA degradation in bacteria

• EC number EC 3.1.13.5: RNase D is involved in the 3'-to-5' processing of pre-tRNAs. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. RNase D is one of the seven exoribonucleases identified in E coli. Transfer RNA (abbreviated tRNA) is a small RNA (usually about 74-95 nucleotides that transfers a specific Amino acid to a growing polypeptide chain at

• EC number 3. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. 1. ??: RNase T is the major contributor for the 3'-to-5' maturation of many stable RNAs.

• EC 3.1.13.3: Oligoribonuclease degrades short oligonucleotides to mononucleotides. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. Oligonucleotidase is an Exoribonuclease derived from Flammulina velutipes.

• EC 3.1.11.1: Exoribonuclease I degrades single-stranded RNA from 5'-to-3', exists only in eukaryotes. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. XRN1 is an Exoribonuclease enzyme This enzyme is involves in 5’ to 3’ RNA degradation

• EC 3.1.13.1: Exoribonuclease II is a close homolog of Exoribonuclease I. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. XRN2 is an Exoribonuclease Enzyme.

External links

• IUBMB Enzyme Database for EC 3.1

• Integrated Enzyme Database for EC 3.1

References

• D'Alessio G and Riordan JF, eds. (1997) Ribonucleases: Structures and Functions, Academic Press.
• Gerdes K, Christensen SK and Lobner-Olesen A (2005). "Prokaryotic toxin-antitoxin stress response loci". Nat. Rev. Microbiol. (3): 371-382.

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