EC Explorer

4.6.1.21

Enterobacter ribonuclease

RNA containing adenosine-cytidine + H₂O = an [RNA fragment]-3′-cytidine-3′-phosphate + a 5′-a hydroxy-adenosine -3′-[RNA fragment] (overall reaction);;(1a) RNA containing adenosine-cytidine = an [RNA fragment]-3′-cytidine-2′,3′-cyclophosphate + a 5′-a hydroxy-adenosine -3′-[RNA fragment];;(1b) an [RNA fragment]-3′-cytidine-2′,3′-cyclophosphate + H₂O = an [RNA fragment]-3′-cytidine-3′-phosphate

[RNA]-adenosine-cytidine 5′-hydroxy-adenosoine ribonucleotide-3′-[RNA fragment]-lyase (cyclicizing; [RNA fragment]-3′-cytidine-2′,3′-cyclophosphate-forming and hydrolysing)

395640-99-0

Preference for cleavage at Cp-A bonds. Homopolymers of A, U or G are not hydrolysed. CpG bonds are hydrolysed less well and there is no detectable hydrolysis between two purines or two pyrimidines. The enzyme catalyses a two-stage endonucleolytic cleavage. The first reaction produces 5′-hydroxy-phosphooligonucletides and 3′-phosphooligonucleotides ending a with 2′,3′-cyclic phosphodiester, which are released from the enzyme. The enzyme then hydrolyses these cyclic compounds in a second reaction that takes place only when all the susceptible 3′,5′-phosphodiester bonds have been cyclised. The second reaction is a reversal of the first reaction using the hydroxyl group of water instead of the 5′-hydroxyl group of ribose. The overall process is that of a phosphorus-oxygen lyase followed by hydrolysis to form the 3′-nucleotides.

created 1978 as EC 3.1.27.6, modified 1981, transferred 2018 to 4.6.1.21