Primary folding dynamics of sperm whale apomyoglobin: Core formation

Miriam Gulotta, Eduard Rogatsky, Robert Callender, R. Brian Dyer

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The structure, thermodynamics, and kinetics of heat-induced unfolding of sperm whale apomyoglobin core formation have been studied. The most rudimentary core is formed at pH* 3.0 and up to 60 mM NaCl. Steady state for ultraviolet circular dichroism and fluorescence melting studies indicate that the core in this acid-destabilized state consists of a heterogeneous composition of structures of ∼26 residues, two-thirds of the number involved for horse heart apomyoglobin under these conditions. Fluorescence temperature-jump relaxation studies show that there is only one process involved in Trp burial. This occurs in 20 μs for a 7° jump to 52°C, which is close to the limits placed by diffusion on folding reactions. However, infrared temperature jump studies monitoring native helix burial are biexponential with times of 5 μs and 56 μs for a similar temperature jump. Both fluorescence and infrared fast phases are energetically favorable but the slow infrared absorbance phase is highly temperature-dependent, indicating a substantial enthalpic barrier for this process. The kinetics are best understood by a multiple-pathway kinetics model. The rapid phases likely represent direct burial of one or both of the Trp residues and parts of the G- and H-helices. We attribute the slow phase to burial and subsequent rearrangement of a misformed core or to a collapse having a high energy barrier wherein both Trps are solvent-exposed.

Original languageEnglish (US)
Pages (from-to)1909-1918
Number of pages10
JournalBiophysical Journal
Volume84
Issue number3
StatePublished - Mar 1 2003

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Sperm Whale
Burial
Temperature
Fluorescence
Circular Dichroism
Thermodynamics
Freezing
Horses
Hot Temperature
Acids
apomyoglobin

ASJC Scopus subject areas

  • Biophysics

Cite this

Gulotta, M., Rogatsky, E., Callender, R., & Dyer, R. B. (2003). Primary folding dynamics of sperm whale apomyoglobin: Core formation. Biophysical Journal, 84(3), 1909-1918.

Primary folding dynamics of sperm whale apomyoglobin : Core formation. / Gulotta, Miriam; Rogatsky, Eduard; Callender, Robert; Dyer, R. Brian.

In: Biophysical Journal, Vol. 84, No. 3, 01.03.2003, p. 1909-1918.

Research output: Contribution to journalArticle

Gulotta, M, Rogatsky, E, Callender, R & Dyer, RB 2003, 'Primary folding dynamics of sperm whale apomyoglobin: Core formation', Biophysical Journal, vol. 84, no. 3, pp. 1909-1918.
Gulotta, Miriam ; Rogatsky, Eduard ; Callender, Robert ; Dyer, R. Brian. / Primary folding dynamics of sperm whale apomyoglobin : Core formation. In: Biophysical Journal. 2003 ; Vol. 84, No. 3. pp. 1909-1918.
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