caa a22 4500 397555881 CHVBK 20180308164801.0 cr unu---uuuuu 161202e199601 xx s 000 0 eng 10.1093/oxfordjournals.jbchem.a021221 doi (NATIONALLICENCE)oxford-10.1093/oxfordjournals.jbchem.a021221 Enzymatic Properties of Mutant Enzymes at Trp49 and Tyr57 of RNase Rh from Rhizopus niveus [Elektronische Daten] [Kazuko Ohgi, Mitsuaki Takeuchi, Masanori Iwama, Masachika Irie] In order to establish the role of Tyr57 and Trp49 in the enzymatic reaction of RNase Rh, several mutant enzymes at Tyr57 and Trp49 were prepared by protein engineering and their enzymatic properties were investigated. Among the four mutant enzymes at Trp49 (W49F, W49Y, W49A, and W49I), W49F showed 16% of the activity of the native enzyme, but the others (W49Y, W49A, and W49I) showed greatly decreased activity. The data showed that Trp49 is very important for the enzyme activity. Among 8 mutant enzymes at the 57th position, Y57F and Y57W showed similar enzymatic activity toward RNA to that of the wild-type enzyme, but the others (Y57G, Y57A, Y57V, Y57M, and Y57K) are more active toward RNA and less active toward XpGs. The reason for the apparent increase for RNA activity is discussed from the view point of substrate inhibition. It is noteworthy that W49F and Y57W became more pyrimidine base- and purine base-preferential, respectively. © by the Journal of Biochemistry Regular Papers nationallicence base non-specific ribonuclease nationallicence mechanism of enzymatic action nationallicence Rhizopus niveus nationallicence ribonuclease nationallicence tyrosine residue nationallicence tryptophan residue nationallicence Ohgi Kazuko Department of Microbiology, Hoshi College of Pharmacy, 2-4-41 Ebara, Shinagawa-ku, Tokyo142 aut Takeuchi Mitsuaki Department of Microbiology, Hoshi College of Pharmacy, 2-4-41 Ebara, Shinagawa-ku, Tokyo142 aut Iwama Masanori Department of Microbiology, Hoshi College of Pharmacy, 2-4-41 Ebara, Shinagawa-ku, Tokyo142 aut Irie Masachika Department of Microbiology, Hoshi College of Pharmacy, 2-4-41 Ebara, Shinagawa-ku, Tokyo142 aut The Journal of Biochemistry Oxford University Press 119/1(1996-01), 9-15 0021-924X 119:1<9 1996 119 jbchem https://doi.org/10.1093/oxfordjournals.jbchem.a021221 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/oxfordjournals.jbchem.a021221 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ohgi Kazuko Department of Microbiology, Hoshi College of Pharmacy, 2-4-41 Ebara, Shinagawa-ku, Tokyo142 aut NATIONALLICENCE 700 1- Takeuchi Mitsuaki Department of Microbiology, Hoshi College of Pharmacy, 2-4-41 Ebara, Shinagawa-ku, Tokyo142 aut NATIONALLICENCE 700 1- Iwama Masanori Department of Microbiology, Hoshi College of Pharmacy, 2-4-41 Ebara, Shinagawa-ku, Tokyo142 aut NATIONALLICENCE 700 1- Irie Masachika Department of Microbiology, Hoshi College of Pharmacy, 2-4-41 Ebara, Shinagawa-ku, Tokyo142 aut NATIONALLICENCE 773 0- The Journal of Biochemistry Oxford University Press 119/1(1996-01), 9-15 0021-924X 119:1<9 1996 119 jbchem Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford