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J Sabelko

Publications and source records attributed to J Sabelko.

4 recordsLinked to original sources
PubMed2000

Submicrosecond real-time fluorescence sampling: application to protein folding.

Time-resolved fluorescence detection has become a central tool in the study of protein folding. This article briefly reviews modern fluorescence techniques and then focuses on recent improvements made possible by array photomultipliers, computer-controlled data gating, and long-memory multi-channel digitizers. It is now possible to detect fluorescence wavelength profiles and/or fluorescence decay transients very cost effectively with sub-microsecond kinetic time resolution out to long times. Folding kinetics can be analyzed by singular value decomposition (SVD) or chi-analysis. The latter provides an objective method for detecting nonexponential kinetics in two-state systems.

Equipment Design↗
PubMed1999

Observation of strange kinetics in protein folding.

Highly nonexponential folding kinetics in aqueous solution have been observed during temperature jump-induced refolding of two proteins, yeast phosphoglycerate kinase and a ubiquitin mutant. The observations are most easily interpreted in terms of downhill folding, which posits a heterogeneous ensemble of structures en route to the folded state. The data are also reconciled with exponential kinetics measured under different experimental conditions and with titration experiments indicating cooperative folding.

Amino Acid Substitution↗
PubMed1996

Direct observation of fast protein folding: the initial collapse of apomyoglobin.

The rapid refolding dynamics of apomyoglobin are followed by a new temperature-jump fluorescence technique on a 15-ns to 0.5-ms time scale in vitro. The apparatus measures the protein-folding history in a single sweep in standard aqueous buffers. The earliest steps during folding to a compact state are observed and are complete in under 20 micros. Experiments on mutants and consideration of steady-state CD and fluorescence spectra indicate that the observed microsecond phase monitors assembly of an A x (H x G) helix subunit. Measurements at different viscosities indicate diffusive behavior even at low viscosities, in agreement with motions of a solvent-exposed protein during the initial collapse.

Animals↗