Open AccessProbing Cytochrome c Folding Transitions upon Phototriggered Environmental Perturbations Using Time-Resolved X-ray Scattering
Author(s) -
Dolev Rimmerman,
Denis Leshchev,
Darren J. Hsu,
Jiyun Hong,
Baxter Abraham,
Robert Henning,
Irina Kosheleva,
Lin X. Chen
Publication year - 2018
Publication title -
the journal of physical chemistry. b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 392
eISSN - 1520-6106
pISSN - 1520-5207
DOI - 10.1021/acs.jpcb.8b03354
Subject(s) - chemistry , cytochrome c , heme , electron transfer , crystallography , active site , molecular dynamics , protein folding , folding (dsp implementation) , photochemistry , metalloprotein , chemical physics , biophysics , computational chemistry , biology , biochemistry , electrical engineering , mitochondrion , enzyme , engineering
Direct tracking of protein structural dynamics during folding-unfolding processes is important for understanding the roles of hierarchic structural factors in the formation of functional proteins. Using cytochrome c (cyt c) as a platform, we investigated its structural dynamics during folding processes triggered by local environmental changes (i.e., pH or heme iron center oxidation/spin/ligation states) with time-resolved X-ray solution scattering measurements. Starting from partially unfolded cyt c, a sudden pH drop initiated by light excitation of a photoacid caused a structural contraction in microseconds, followed by active site restructuring and unfolding in milliseconds. In contrast, the reduction of iron in the heme via photoinduced electron transfer did not affect conformational stability at short timescales (<1 ms), despite active site coordination geometry changes. These results demonstrate how different environmental perturbations can change the nature of interaction between the active site and protein conformation, even within the same metalloprotein, which will subsequently affect the folding structural dynamics.