ID   4.6.1.21
DE   Enterobacter ribonuclease.
CA   RNA containing adenosine-cytidine + H2O = an [RNA fragment]-3'-cytidine-
CA   3'-phosphate + a 5'-a hydroxy-adenosine -3'-[RNA fragment].
CC   -!- Preference for cleavage at Cp-A bonds.
CC   -!- Homopolymers of A, U or G are not hydrolyzed.
CC   -!- CpG bonds are hydrolyzed less well and there is no detectable
CC       hydrolysis between two purines or two pyrimidines.
CC   -!- The enzyme catalyzes a two-stage endonucleolytic cleavage.
CC   -!- The first reaction produces 5'-hydroxy-phosphooligonucletides and
CC       3'-phosphooligonucleotides ending a with 2',3'-cyclic phosphodiester,
CC       which are released from the enzyme.
CC   -!- The enzyme then hydrolyzes these cyclic compounds in a second
CC       reaction that takes place only when all the susceptible
CC       3',5'-phosphodiester bonds have been cyclised.
CC   -!- The second reaction is a reversal of the first reaction using the
CC       hydroxyl group of water instead of the 5'-hydroxyl group of ribose.
CC   -!- The overall process is that of a phosphorus-oxygen lyase followed by
CC       hydrolysis to form the 3'-nucleotides.
CC   -!- Formerly EC 3.1.27.6.
DR   P21338, RNI_ECOLI  ;
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