Peroxidase activity of in vitro‐selected 2′‐amino RNAs

Peroxidase activities of RNAs containing 2′‐amino groups, which were selected as aptamers binding to N ‐methylmesoporphyrin IX, were investigated. Some clones promoted the oxidation reaction of 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) with hydrogen peroxide (H 2 O 2 ) in the presence of iron(III)‐protoporphyrin (hemin), whereas others did not. Each of them had a different substrate specificity. One of the active clones promoted the oxidation of o ‐dianisidine and β‐nicotinamide adenine dinucleotide reduced form (NADH) with H 2 O 2 5 and 15 times faster than hemin only, respectively. On the other hand, one clone that was inactive on oxidation of ABTS exhibited the same level of activity on oxidation of o ‐dianisidine as that shown by the clone active on ABTS but no activity on NADH. By in vitro selection, we can produce various types of peroxidase‐like non‐natural RNAs. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 463–468, 2001.