Correlating Ultrafast Function with Structure in Single Crystals of the Photosynthetic Reaction Center

• Published in: Biochemistry (Easton) Vol. 47; no. 44; pp. 11387 - 11389
• Main Authors: Huang, Libai, Wiederrecht, Gary P, Utschig, Lisa M, Schlesselman, Sandra L, Xydis, Christina, Laible, Philip D, Hanson, Deborah K, Tiede, David M
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 04-11-2008
• Subjects: Crystallization; Crystallography, X-Ray; Electron Transport; Kinetics; Models, Molecular; Multiprotein Complexes - chemistry; Photosynthetic Reaction Center Complex Proteins - chemistry; Photosynthetic Reaction Center Complex Proteins - metabolism; Rhodobacter sphaeroides - chemistry; Rhodobacter sphaeroides - metabolism; Solutions; Spectrophotometry; Thermodynamics
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi801026g

Femtosecond transient absorbance spectroscopy was applied to the study of primary electron transfer in single reaction center crystals from Rhodobacter sphaeroides. Polarized transient absorption spectra of individual crystals are shown to correlate with polarized ground-state absorption spectra and to track cofactor transition moment directions calculated from the crystallographic structure. Electron transfer from the bacteriochlorophyll dimer to the bacteriopheophytin acceptor was found to be multiphasic in crystals and ∼2-fold slower than in solution. This work demonstrates the ability to resolve ultrafast photosynthetic function in single crystals and allows ultrafast function to be directly correlated with structure.