A1 Journal article – refereed
Genetic engineering of Escherichia coli inorganic pyrophosphatase
Tyr55 and Tyr141 are important for the structural integrity





List of Authors: LAHTI R, SALMINEN T, LATONEN S, HEIKINHEIMO P, POHJANOKSA K, HEINONEN J
Publisher: SPRINGER VERLAG
Publication year: 1991
Journal: European Journal of Biochemistry
Journal name in source: EUROPEAN JOURNAL OF BIOCHEMISTRY
Journal acronym: EUR J BIOCHEM
Volume number: 198
Issue number: 2
Number of pages: 5
ISSN: 0014-2956

Abstract
Interestingly, substitution of the tyrosines (Tyr51, Tyr55 and Tyr141) conserved with the amino acid sequence of yeast PP(i)ase [Lahti, R., Kolakowski, L. F., Heinonen, J., Vihinen, M., Pohjanoksa, K. and Cooperman, B. (1990) Biochim. Biophys. Acta 1038, 338-345] exerted the most drastic effects on the structure and activity of E. coli PP(i)ase. PP(i)ase variants YF51, YF55 and YF141 had 64%, 7% and 22% of the wild-type PP(i)ase activity, respectively. Furthermore, PP(i)ase variant YF141 had an increased sensitivity to heat denaturation, whereas mutant PP(i)ase YF55 displayed a profound conformational change, as demonstrated by the binding of the fluorescent dye 9-(diethylamino)-5H-benzo(alpha) phenoxazine-5-one (Nile red) that monitors the hydrophobicity of protein surfaces. None of the tyrosines of E. coli PP(i)ase seem to be essential for catalysis, but Tyr55 and Tyr141 are important for the structural integrity of E. coli PP(i)ase.

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