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The bulk of the fluorescence of lysozyme is located in Trp 62 and Trp 108. By examination of the fluorescence of derivatives in which Trp 62 and/or Trp 108 are specifically oxidized, it has been possible to detect a pH-dependent interaction between tryptophan residues. This interaction is interpreted as energy transfer from Trp 108 to Trp 62.
The interaction between protein and water is of fundamental importance for processes ranging from protein folding and enzymatic activity to anhydrobiosis. In this letter we bring together results from diverse types of measurements to give a unified picture of the hydration process for lysozyme. The data come principally from experiments with protein films(More)
Dielectric losses were measured for lysozyme powders of varied hydration level by a dielectric-gravimetric technique in the frequency range of 10 kHz to 10 MHz. The relaxation showed an isotope effect and pH dependence, indicating that the inferred conductivity is protonic. The transport process is likely restricted to the surface of individual(More)
Calorimetric measurements of the heat capacity of the lysozyme-water system have been carried out over the full range of system composition at 25 degrees C. The partial specific heat capacity of the protein in dilute solution is 1.483 +/- 0.009 J K-1 g-1. The heat capacity of the dry protein is 1.26 +/- 0.01 J K-1 g-1. The system heat capacity responds(More)
Specific cleavage of LexA repressor plays a crucial role in the SOS response of Escherichia coli. In vivo, cleavage requires an activated form of RecA protein. However, previous work has shown that the mechanism of cleavage is unusual, in that the chemistry of cleavage is probably carried out by residues in the repressor, and not those in RecA; RecA appears(More)
LexA repressor of Escherichia coli and phage lambda repressor are inactivated in vivo and in vitro by specific cleavage of an Ala-Gly peptide bond in reactions requiring RecA protein. At mildly alkaline pH, the in vitro cleavage reaction also proceeds spontaneously, suggesting that peptide bond hydrolysis is an activity of the repressors rather than of(More)