Protein Engineering and Biophysical Studies of Metal Binding Proteins
As will be amply illustrated during this Advanced Summer School, basic studies of enzyme mechanisms, protein stability, folding-unfolding pathways, protein-protein and protein-nucleic acid interactions have been greatly facilitated through the introduction of recombinant DNA methods and site-specific mutations. Mammalian proteins, which are often difficult to isolate and purify from natural sources, may — provided the gene can be cloned or synthesized — be expressed in a microorganism in substantial quantities. That aspect alone may be crucial for characterization of a protein with biophysical techniques that often require respectable amounts of purified material — NMR spectroscopy is a case in point. Expression of mammalian proteins in a rapidly growing microorganism also makes possible the application of isotope labelling (2H, 13C., 15N, etc.). This is atechnique of increasing importance in the assignment of NMR signals of larger proteins for which spectral crowding and overlap is an experimental obstacle. By means of spectral editing through isotope labelling, it may eventually be possible to study in detail selected areas in large proteins — for example individual domains or the active regions of enzymes (Redfield, 1989) — without the need for a complete assignment of the whole NMR spectrum.
KeywordsRestriction Enzyme Site Chemical Shift Difference Biophysical Study Conformational Heterogeneity Minor Resonance
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