Papers by Robert Blankenship
Trends in Biochemical Sciences, 1998
The evolutionary developments that led to the ability of photosynthetic organisms to oxidize wate... more The evolutionary developments that led to the ability of photosynthetic organisms to oxidize water to molecular oxygen are discussed. Two major changes from a more primitive non-oxygen-evolving reaction center are required: a charge-accumulating system and a reaction center pigment with a greater oxidizing potential. Intermediate stages are proposed in which hydrogen peroxide was oxidized by the reaction center, and an intermediate pigment, similar to chlorophyll d, was present.
Bookmarks Related papers MentionsView impact
Protein science : a publication of the Protein Society, 2015
Native spray has the potential to probe biophysical properties of protein assemblies. Here we rep... more Native spray has the potential to probe biophysical properties of protein assemblies. Here we report an investigation using both ECD top-down sequencing with an FTICR mass spectrometer and ion mobility (IM) measurements on a Q-TOF to investigate the collisionally induced unfolding of a native-like heterogeneous tetrameric assembly, human hemoglobin (hHb) in the gas phase. To our knowledge, this is the first report combining ECD and ion-mobility data on the same target protein assembly to delineate the effects of collisional activation on both assembly size and the extent and location of fragmentation. Although the collision-induced unfolding of the hemoglobin assembly is clearly seen by both IMMS and ECD, the latter delineates the regions that increasingly unfold as the collision energy is increased. The results are consistent with previous outcomes for homogeneous protein assemblies and reinforce our interpretation that activation opens the structure of the protein assembly from th...
Bookmarks Related papers MentionsView impact
Advances in Photosynthesis and Respiration, 2006
Chlorophylls (Chls) are the signature pigments of photosynthetic organisms and have several disti... more Chlorophylls (Chls) are the signature pigments of photosynthetic organisms and have several distinct functions, including photochemical activity and antenna function. Chls carry out reversible photochemical oxidations and reductions, which determine the basic mechanism of functioning of the photosynthetic reaction center (RC). The light-harvesting function of chlorophylls is based on their ability to absorb light over a wide spectral region. The
Bookmarks Related papers MentionsView impact
Advances in Photosynthesis and Respiration, 2003
Robert E. Blankenship Department of Chemistry and Biochemistry, Center for the Study of Early Eve... more Robert E. Blankenship Department of Chemistry and Biochemistry, Center for the Study of Early Events in Photosynthesis, Arizona State University,Tempe, AZ 85287-1604, USA ... John M. Olson* and Mette Miller Institute of Biochemistry, Odense University, DK-5230 Odense M, ...
Bookmarks Related papers MentionsView impact
The journal of physical chemistry. B, Jan 9, 2015
The fate of triplet excited states in the Fenna-Matthew-Olson (FMO) pigment-protein complex is st... more The fate of triplet excited states in the Fenna-Matthew-Olson (FMO) pigment-protein complex is studied by means of time-resolved nanosecond spectroscopy and exciton model simulations. Experiments reveal microsecond triplet excited state energy transfer between the Bacteriochlorophyll (BChl) pigments, but show no evidence of triplet energy transfer to molecular oxygen, which is known to produce highly reactive singlet oxygen and is the leading cause of photo damage in photosynthetic proteins. The FMO complex is exceptionally photo stable despite the fact it contains no carotenoids, which could effectively quench triplet excited states of (bacterio)chlorophylls and are usually found within pigment-protein complexes. It is inferred that the triplet excitation is transferred to the lowest energy pigment, BChl 3, within the FMO complex, whose triplet state energy is shifted by pigment-protein interactions below that of the singlet oxygen excitation. Thus the energy transfer to molecular ...
Bookmarks Related papers MentionsView impact
The Journal of Physical Chemistry, 1996
Light-harvesting chlorosomes in green photosynthetic bacteria are unique in that they contain oli... more Light-harvesting chlorosomes in green photosynthetic bacteria are unique in that they contain oligomers of bacteriochlorophyll (BChl) c, d, and/or e pigments, whose supramolecular structures appear to be governed by pigment−pigment rather than pigment−protein interactions. 1 ...
Bookmarks Related papers MentionsView impact
The Journal of Physical Chemistry, 1994
Page 1. 10322 J. Phys. Chem. 1994, 98, 10322-10334 Femtosecond Spectroscopy of Chlorosome Antenna... more Page 1. 10322 J. Phys. Chem. 1994, 98, 10322-10334 Femtosecond Spectroscopy of Chlorosome Antennas from the Green Photosynthetic Bacterium Chlorojlexus aurantiucus Sergei SavikhinJ Yinwen Zhu,* Su Lin: Robert ...
Bookmarks Related papers MentionsView impact
Photosynthesis research, 1990
Time-resolved fluorescence spectroscopy and global data analysis techniques have been used to stu... more Time-resolved fluorescence spectroscopy and global data analysis techniques have been used to study the flow of excitations in antennae of the green photosynthetic bacteria Chloroflexus aurantiacus and Chlorobium vibrioforme f. thiosulfatophilum. The transfer of energy from bacteriochlorophyll (BChl) c in Chloroflexus or BChl d in Chlorobium to BChl a 795 was resolved in both whole cells and isolated chlorosomes. In Chloroflexus, the decay of excitations in BChl c occurs in ∼16 ps and a corresponding rise in BChl a emission at 805 nm is detected in global analyses. This band then decays in 46 ps in whole cells due to energy transfer into the membrane. The 805 nm fluorescence in isolated chlorosomes shows a fast decay component similar to that of whole cells, which is consistent with trapping by residual membrane antenna complexes. In Chlorobium, the kinetics are sensitive to the presence of oxygen. Under anaerobic conditions, BChl d decays in 66 ps while the lifetime shortens to 11 ...
Bookmarks Related papers MentionsView impact
Photosynthesis research, 2005
Energy transfer processes in the chlorophyll antenna of the PS I-LHCI supercomplexes from the gre... more Energy transfer processes in the chlorophyll antenna of the PS I-LHCI supercomplexes from the green alga Chlamydomonas reinhardtii have been studied at 77 K using transient absorption spectroscopy with multicolor excitation in the 640-670 nm region. Comparison of the kinetic data obtained at low and room temperatures indicates that the slow approximately approximately 100 ps excitation equilibration phase that is characteristic of energy coupling of the LHCI peripheral antenna to the PS I core at physiological temperatures (Melkozernov AN, Kargul J, Lin S, Barber J and Blankenship RE (2004) J Phys Chem B 108: 10547-10555) is not observed in the excitation dynamics of the PS I-LHCI supercomplex at 77 K. This suggests that at low temperatures the peripheral antenna is energetically uncoupled from the PS I core antenna. Under these conditions the observed kinetic phases on the time scales from subpicoseconds to tens of picoseconds represent the superposition of the processes occurring ...
Bookmarks Related papers MentionsView impact
The Journal of physical chemistry, Jan 29, 1996
Energy transfers between the bacteriochlorophyll c and a antennae in light-harvesting chlorosomes... more Energy transfers between the bacteriochlorophyll c and a antennae in light-harvesting chlorosomes from the green bacterium Chloroflexes aurantiacus have been studied in two-color pump-probe experiments with improved sensitivity and wavelength versatility. The BChl c --> BChl a energy transfers are well simulated with biexponential kinetics, with lifetimes of 2-3 and 11 ps. They do not exhibit an appreciable subpicosecond component. In the context of a kinetic model for chlorosomes, these lifetimes suggest that both internal BChl c processes and the BChl c --> BChl a energy-transfer step contribute materially to the empirical rod-to-baseplate energy-transfer kinetics.
Bookmarks Related papers MentionsView impact
Photochemical & Photobiological Sciences, 2005
Pigment-protein complexes enriched in photosystem II (PS II) have been isolated from the chloroph... more Pigment-protein complexes enriched in photosystem II (PS II) have been isolated from the chlorophyll (Chl) d containing cyanobacterium, Acaryochloris marina. A small PS II-enriched particle, we call 'crude reaction centre', contained 20 Chl d, 0.5 Chl a and 1 redox active cytochrome b-559 per 2 pheophytin a, plus the D1 and D2 proteins. A larger PS II-enriched particle, we call 'core', additionally bound the antenna complexes, CP47 and CP43, and had a higher chlorophyll per pheophytin ratio. Pheophytin a could be photoreduced in the presence of a strong reductant, indicating that it is the primary electron acceptor in photosystem II of A. marina. A substoichiometric amount of Chl a (less than one chlorophyll a per 2 pheophytin a) strongly suggests that Chl a does not have an essential role in the photochemistry of PS II in this organism. We conclude that PS II, in A. marina, utilizes Chl d and not Chl a as primary electron donor and that the primary electron acceptor is one of two molecules of pheophytin a.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Analytical biochemistry, Jan 16, 2014
(13)C-metabolism analysis of a microbial community is often hindered by the time-consuming and co... more (13)C-metabolism analysis of a microbial community is often hindered by the time-consuming and complicated separation procedure for a single species. However, a "reporter protein", produced uniquely by one cell type, retains (13)C-fingerprints information in microbial consortia. This study describes the use of photosystem I (PSI), a multi-subunit protein complex universally found in oxygenic phototrophs, as a reliable reporter protein to probe microalgal metabolism (i.e., cyanobacterium Synechocystis 6803) in a mixed culture with heterotrophic bacteria (i.e., Escherichia coli). We demonstrate that efficient purification of PSI and subsequent (13)C-based amino acid analyses may decipher photomixotrophic metabolism of Synechocystis 6803 in the coculture. This study also indicates that a supplement of NaHCO3 at high concentration could significantly improve the robustness of cyanobacterial growth against bacterial contamination.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Biochimica et biophysica acta, 2014
The major light harvesting complex in cyanobacteria and red algae is the phycobilisome (PBS), com... more The major light harvesting complex in cyanobacteria and red algae is the phycobilisome (PBS), comprised of hundreds of seemingly similar chromophores, which are protein bound and assembled in a fashion that enables highly efficient uni-directional energy transfer to reaction centers. The PBS is comprised of a core containing 2-5 cylinders surrounded by 6-8 rods, and a number of models have been proposed describing the PBS structure. One of the most critical steps in the functionality of the PBS is energy transfer from the rod substructures to the core substructure. In this study we compare the structural and functional characteristics of high-phosphate stabilized PBS (the standard fashion of stabilization of isolated complexes) with cross-linked PBS in low ionic strength buffer from two cyanobacterial species, Thermosynechococcus vulcanus and Acaryochloris marina. We show that chemical cross-linking preserves efficient energy transfer from the phycocyanin containing rods to the allo...
Bookmarks Related papers MentionsView impact
Febs Letters, 1975
1. FEBS Lett. 1975 Mar 1;51(1):287-93. Observation of a new EPR transient in chloroplasts that ma... more 1. FEBS Lett. 1975 Mar 1;51(1):287-93. Observation of a new EPR transient in chloroplasts that may reflect the electron donor to photosystem II at room temperature. Blankenship RE, Babcock GT, Warden JT, Sauer K. PMID ...
Bookmarks Related papers MentionsView impact
Febs Letters, 1983
Bookmarks Related papers MentionsView impact
Biochimica et biophysica acta, 2014
The orange carotenoid protein (OCP), a member of the family of blue light photoactive proteins, i... more The orange carotenoid protein (OCP), a member of the family of blue light photoactive proteins, is required for efficient photoprotection in many cyanobacteria. Photoexcitation of the carotenoid in the OCP results in structural changes within the chromophore and the protein to give an active red form of OCP that is required for phycobilisome binding and consequent fluorescence quenching. We characterized the light-dependent structural changes by mass spectrometry-based carboxyl footprinting and found that an α helix in the N-terminal extension of OCP plays a key role in this photoactivation process. Although this helix is located on and associates with the outside of the β-sheet core in the C-terminal domain of OCP in the dark, photoinduced changes in the domain structure disrupt this interaction. We propose that this mechanism couples light-dependent carotenoid conformational changes to global protein conformational dynamics in favor of functional phycobilisome binding, and is an e...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Uploads
Papers by Robert Blankenship