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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)
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)
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)
Binding of carbon monoxide to beta chains of hemoglobin Zürich has been studied by flash photolysis over the time range of nanoseconds to seconds at temperatures from 20 to 300 K. From 20 to 200 K a single rebinding process (process I) is seen, characterized by a distribution of barrier heights with a peak enthalpy of 2.3 kJ/mol. Above 200 K some ligands(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)
BACKGROUND For many proteins, compact states appear long before the rate-limiting step in the formation of the native structure. A key issue is whether the initial collapse of the chain is driven by random or more specific hydrophobic interactions. RESULTS Hydrogen-exchange labeling coupled with NMR was used to monitor the formation of stable(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)
Hydrogen-deuterium exchange experiments have been used previously to investigate the structures of well defined states of a given protein. These include the native state, the unfolded state, and any intermediates that can be stably populated at equilibrium. More recently, the hydrogen-deuterium exchange technique has been applied in kinetic labeling(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)