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Fluorescence Characteristics of a Tryptophan Mutant of Leucine-responsive Regulatory Protein (Lrp)

트립토판 돌연변이 루신-반응 조절 단백질의 형광 특성

  • Pokoo, Robert (Department of Biochemistry, Chungnam National University) ;
  • Lee, Eui Ho (Department of Biochemistry, Chungnam National University) ;
  • Lee, Chan Yong (Department of Biochemistry, Chungnam National University)
  • Received : 2014.11.10
  • Accepted : 2014.12.03
  • Published : 2014.12.31

Abstract

Leucine-responsive Regulatory Protein (Lrp) from Escherichia coli is an 18.8 kDa protein composed of 164 amino acids. Wild type Lrp (Lrp Wt) does not possess any tryptophan amino acid which has strong intrinsic fluorescence, whereas the mutant Lrp R145W contains a single tryptophan at the position 145 in the leucine-responsive domain. To investigate the fluorescence character, the Lrp R145W and Lrp Wt proteins were purified. The fluorescence intensity of Lrp R145W is much higher than that of wild type protein, and the intensity of Lrp R145W was decreased by binding to its specific DNA designed from ilvIH operon and to L-leucine. In addition, the tryptophan fluorescence intensity of Lrp R145W was strongly quenched by addition of acrylamide even in the least amount of concentration as well as by urea. The data obtained from this study may give valuable information on the three dimensional structure of Lrp R145W.

Keywords

fluorescence;global regulatory protein (Lrp);leucine

Acknowledgement

Supported by : Chungnam National University

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