A study of energetics of cooperative interaction using a mutant λ-repressor

Jana, Nandan K. ; Deb, Sunanda ; Bhattacharyya, Bhabatarak ; Mandal, Nitai C. ; Roy, Siddhartha (2000) A study of energetics of cooperative interaction using a mutant λ-repressor Protein Engineering Design & Selection, 13 (9). pp. 629-633. ISSN 1741-0126

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Official URL: http://peds.oxfordjournals.org/content/13/9/629.ab...

Related URL: http://dx.doi.org/10.1093/protein/13.9.629

Abstract

A λ-repressor mutant, S228N, which is defective in tetramer formation in the free state but retains full cooperativity, was studied in detail. Isolated single operator-bound S228N repressor shows association properties similar to those of the wild-type repressor. Fluorescence anisotropy studies with dansyl chloride-labeled repressor show a dimer-monomer dissociation constant of around 10-5 M. The structure of the mutant repressor was studied by circular dichroism, acrylamide quenching and sulfhydryl reactivity at protein concentrations of ≤ 10-6 M, where it is predominantly monomeric. The results suggest no significant perturbations in the structure of the S228N mutant repressor from that of the wild-type repressor. Urea denaturation studies also indicate no significant change in the stability of the repressor. The results were used to calculate energetics of loop formation in the cooperative binding process.

Item Type:Article
Source:Copyright of this article belongs to Oxford University Press.
Keywords:Cooperativity; Free Energy; Loop Repressor; Transcription
ID Code:26156
Deposited On:06 Dec 2010 13:00
Last Modified:17 May 2016 09:30

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