Effects of amino acid substitutions on the pressure denaturation of staphylococcal nuclease as monitored by fluorescence and nuclear magnetic resonance spectroscopy

In the present study we have used high hydrostatic pressure coupled with either time-resolved and steady-state fluorescence or NMR spectroscopy in order to investigate the effects of amino acid substitutions on the high-pressure denaturation properties of staphylococcal nuclease. This protein has been shown previously to be structurally heterogeneous in its native state. On the NMR time scale, four distinct interconverting conformational forms arise from the population of both cis and trans Xaa-Pro peptide bonds (His 46 -Pro 47 and Lys 116 -Pro 117 ) [Evans et al. (1989) Biochemistry 28, 362; Loh et al. (1991) in Techniques in Protein Chemistry II, pp 275-282, Academic Press, New York]