EC Number   |
Reaction |
Reference |
|---|
   4.6.1.18 | an [RNA] containing cytidine + H2O = an [RNA]-3'-cytidine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA] |
specifically located basic residues, together with the lack of a negative charge and/or the presence of a glycine at position 38, may contribute to make the enzymatic degradation of the polyanionic double-helical substrate more efficient |
654672 |
| 4.6.1.18 | an [RNA] containing cytidine + H2O = an [RNA]-3'-cytidine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA] |
the catalytic site of the enzyme is mainly composed of His12, His119, Gln11, Lys41 and Asp121. The conformation of Lys41 and Gln11 are pH dependent and their occurrence is correlated to the release of a sulfate ion from the active site at neutral pH. The sulfate anion is progressively released with pH and water molecules occupy the active site at pH 7.1. The enzyme adopts different conformational states in different pH conditions. In the protonated state, Lys41 points towards the active site both in the presence and in the absence of sulfate and acts as a general base during catalysis |
654126 |
| 4.6.1.18 | an [RNA] containing cytidine + H2O = an [RNA]-3'-cytidine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA] |
the enzyme is composed of 124 amino acid residues. The amino acid residues involved in catalysis are His12, His119 and Lys41. The enzyme has six substrate binding subsites. One of them, B1, binds only to pyrimidine nucleotides and prefers to bind cytidine rather than uridine. Thr45 of the B1 subsite contributes to the enzyme substrate specificity and plays an important role in catalysis. Phe120 in the B1 subsite enhances substrate binding with the aid of its pi electron and hydrophobicity. Asn71 in the B2 subsite is responsible for productive interactions leading to efficient activity, and Glu111 in the same subsite contributes to substrate binding only in the binding of guanosine. Lys7, Arg10 and Gln11 in the P2 subsite also play an important role in catalysis. Some amino acid residues are located in the vicinity of the catalytic residues and contribute to the catalytic reaction by interacting with catalytic residues. Lys7, Arg10 and Lys66 maintain the optimum pKa of His12 and His119. Asp121 positions the proper tautomer of His119. Phe120 is responsible for the strict positioning of His119, and contributes to conformational stability. Tyr97 is involved in maintaining the correct position of Lys41. Cys65-Cys72 are located close to the catalytic and substrate binding residues and contribute to the proper spatial alignment of these residues |
656308 |
| 4.6.1.18 | an [RNA] containing cytidine + H2O = an [RNA]-3'-cytidine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA] |
two isoforms of dimeric enzyme, D-I and D-II |
655538 |
| 4.6.1.18 | an [RNA] containing cytidine = an [RNA]-3'-cytidine-2',3'-cyclophosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA] |
(1a) |
- |
| 4.6.1.18 | an [RNA] containing uridine + H2O = an [RNA]-3'-uridine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA] |
(2) |
- |
| 4.6.1.18 | an [RNA] containing uridine = an [RNA]-3'-uridine-2',3'-cyclophosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA] |
(2a) |
- |
| 4.6.1.18 | an [RNA]-3'-cytidine-2',3'-cyclophosphate + H2O = an [RNA]-3'-cytidine-3'-phosphate |
(1b) |
- |
| 4.6.1.18 | an [RNA]-3'-uridine-2',3'-cyclophosphate + H2O = an [RNA]-3'-uridine-3'-phosphate |
(2b) |
- |
