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With the use of one-dimensional 1H nuclear magnetic resonance, two-dimensional correlated spectroscopy, and two-dimensional nuclear Overhauser enhancement spectroscopy, the exchange mechanisms for numerous individual amide protons in the basic pancreatic trypsin inhibitor (BPTI) were investigated over a wide range of p2H and temperature. Correlated exchange(More)
The complex kinetic behavior commonly observed in protein folding studies suggests that a heterogeneous population of molecules exists in solution and that a number of discrete steps are involved in the conversion of unfolded molecules to the fully native form. A central issue in protein folding is whether any of these kinetic events represent(More)
The formation of hydrogen-bonded structure in the folding reaction of ubiquitin, a small cytoplasmic protein with an extended beta-sheet and an alpha-helix surrounding a pronounced hydrophobic core, has been investigated by hydrogen-deuterium exchange labeling in conjunction with rapid mixing methods and two-dimensional NMR analysis. The time course of(More)
A method to be used for experimental studies of protein folding introduced by Schmid and Baldwin (J. Mol. Biol. 135: 199-215, 1979), which is based on the competition between amide hydrogen exchange and protein refolding, was extended by using rapid mixing techniques and 1H NMR to provide site-resolved kinetic information on the early phases of protein(More)
In spite of marginal sequence homology, cytochrome c2 from photosynthetic bacteria and the mitochondrial cytochromes c exhibit some striking structural similarities, including the tertiary arrangement of the three main helices. To compare the folding mechanisms for these two distantly related groups of proteins, equilibrium and kinetic measurements of the(More)
Exchange rates of individual amide protons in the polypeptide backbone of a protein can be measured by two-dimensional NMR. They serve to locate structure in folding intermediates. To determine the pathway by which a protein folds up, it is necessary to characterize the structures of folding in-termediates and also to place these intermediates in the(More)
The magnetic susceptibility of photodissociated carbon monoxy myoglobin has been measured over the temperature range from 1.7 to 25 K at 10 and 50 kG with a superconducting susceptometer. The spin and the crystal field parameters of the iron ion were extracted by a spin Hamiltonian approach. Under equivalent conditions the magnetic susceptibility of deoxy(More)
A novel experiment is described for measurements of amide proton exchange rates in proteins with a time resolution of about 1 s. A flow apparatus was used to expose protein solutions in 2H2O first to high temperature for a predetermined time period, during which 1H-2H exchange proceeded, and then to ice-water. The technique was applied for exchange studies(More)