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We report on the unexpected structural changes caused by substitution of acidic amino acids in the Q(B) binding pocket of the bacterial photosynthetic reaction center by alanines. The mutations targeted key residues L212Glu and L213Asp of this transmembrane protein-cofactor complex. The amino acid substitutions in the L212Ala-L213Ala mutant reaction center(More)
High-throughput approaches for gene cloning and expression require the development of new nonstandard tools for molecular biologists and biochemists. We introduce a Web-based tool to design primers specifically for the generation of expression clones for both laboratory-scale and high-throughput projects. The application is designed not only to allow the(More)
We present computer simulations of excited state dynamics in models of PS I and PS II which are based upon known structural and spectral properties of the antennae. In particular, these models constrain the pigment binding sites to three-dimensional volumes determined from molecular properties of the antenna complexes. The simulations demonstrate that(More)
The efficiency of triplet energy transfer from the special pair (P) to the carotenoid (C) in photosynthetic reaction centers (RCs) from a large family of mutant strains has been investigated. The mutants carry substitutions at positions L181 and/or M208 near chlorophyll-based cofactors on the inactive and active sides of the complex, respectively.(More)
Subpicosecond transient absorption studies are reported for a set of Rhodobacter (R.) capsulatus bacterial photosynthetic reaction centers (RCs) designed to probe the origins of the unidirectionality of charge separation via one of two electron transport chains in the native pigment-protein complex. All of the RCs have been engineered to contain a(More)
Symmetry-related branches of electron-transfer cofactors-initiating with a primary electron donor (P) and terminating in quinone acceptors (Q)-are common features of photosynthetic reaction centers (RC). Experimental observations show activity of only one of them-the A branch-in wild-type bacterial RCs. In a mutant RC, we now demonstrate that electron(More)
We report time-resolved optical measurements of the primary electron transfer reactions in Rhodobacter capsulatus reaction centers (RCs) having four mutations: Phe(L181) --> Tyr, Tyr(M208) --> Phe, Leu(M212) --> His, and Trp(M250) --> Val (denoted YFHV). Following direct excitation of the bacteriochlorophyll dimer (P) to its lowest excited singlet state P,(More)
Isolated photosystem I (PSI) reaction center/core antenna complexes (PSI-40) were platinized by reduction of [PtCl6]2- at 20 degrees C and neutral pH. PSI particles were visualized directly on a gold surface by scanning tunneling microscopy (STM) before and after platinization. STM results showed that PSI particles were monomeric and roughly ellipsoidal(More)
Integral membrane proteins (IMPs) are crucial biological components, mediating the transfer of material and information between cells and their environment. Many IMPs have proven to be difficult to isolate and study. High-resolution structural information on this class of proteins is limited, largely because of difficulties in generating soluble forms of(More)
Membrane protein manipulation is a challenging task owing to limited tertiary and quaternary structural stability once the protein has been removed from a lipid bilayer. Such instability can be overcome by embedding membrane proteins in detergent micelles formed from amphiphiles with carefully tuned properties. This study introduces a class of(More)