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Identification of two essential histidine residues of ribonuclease T2 from <em>Aspergillus oryzae</em>.

Authors :
Kawata, Yasushi
Sakiyama, Fumio
Hayashi, Fumiaki
Kyogoku, Yoshimasa
Source :
European Journal of Biochemistry; 1/12/90, Vol. 187 Issue 1, p255-262, 8p
Publication Year :
1990

Abstract

Ribonuclease (RNase) T2 from Aspergillus oryzae was modified by diethyl pyrocarbonate and iodoacetic acid. RNase T2 was rapidly inactivated by diethyl pyrocarbonate above pH 6.0 and by incorporation of a carboxymethyl group. No inactivation occurred m the presence of 3′AMP. &lt;superscript&gt;1&lt;/superscript&gt;H-NMR titration and photo-chemically induced dynamic nuclear polarization experiments demonstrated that two histidine residues were involved in the active site of RNase T2. Furthermore, analysis of inactive carboxymethylated RNase T2 showed that both His53 and Hisl15 were partially modified to yield a total of one mole of N′-carboxymethylhistidine/mole enzyme. The results indicate that the two histidine residues in the active site of RNase T2 are essential for catalysis and that modification of either His53 or Hisl15 inactivates the enzyme. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00142956
Volume :
187
Issue :
1
Database :
Complementary Index
Journal :
European Journal of Biochemistry
Publication Type :
Academic Journal
Accession number :
13718077
Full Text :
https://doi.org/10.1111/j.1432-1033.1990.tb15303.x