Robert R. Birge

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The interaction of alamethicin with artificial lecithin multilamellar dispersions was investigated by nuclear magnetic resonance (NMR) and Raman spectroscopies. 31P NMR studies revealed perturbation of the lipid head groups in the presence of the icosapeptide. Simulation of the 31P NMR spectra indicated that the observed spectral changes could be attributed(More)
Retinal photoreceptors are noisy. They generate discrete electrical events in the dark indistinguishable from those evoked by light and thereby limit visual sensitivity at low levels of illumination. The random spontaneous events are strongly temperature-dependent and have been attributed to thermal isomerizations of the vitamin A chromophore of rhodopsin,(More)
The main-form (MFPCP) and high-salt (HSPCP) peridinin-chlorophyll a proteins from the dinoflagellate Amphidinium carterae were investigated using absorption, fluorescence, fluorescence excitation, two-photon, and fast-transient optical spectroscopy. Pigment analysis has demonstrated previously that MFPCP contains eight peridinins and two chlorophyll (Chl) a(More)
Carotenes and xanthophylls are well known to act as electron donors in redox processes. This ability is thought to be associated with the inhibition of oxidative reactions in reaction centers and light-harvesting pigment–protein complexes of photosystem II (PSII). In this work, cation radicals of neoxanthin, violaxanthin, lutein, zeaxanthin,(More)
The peridinin-chlorophyll a-protein (PCP) of dinoflagellates is unique among the large variety of natural photosynthetic light-harvesting systems. In contrast to other chlorophyll protein complexes, the soluble PCP is located in the thylakoid lumen, and the carotenoid pigments outnumber the chlorophylls. The structure of the PCP complex consists of two(More)
Short-wavelength visual pigments (SWS1) have lambda(max) values that range from the ultraviolet to the blue. Like all visual pigments, this class has an 11-cis-retinal chromophore attached through a Schiff base linkage to a lysine residue of opsin apoprotein. We have characterized a series of site-specific mutants at a conserved acidic residue in(More)
Two short-wavelength cone opsins, frog (Xenopus laevis) violet and mouse UV, were expressed in mammalian COS1 cells, purified in delipidated form, and studied using cryogenic UV-vis spectrophotometry. At room temperature, the X. laevis violet opsin has an absorption maximum at 426 nm when generated with 11-cis-retinal and an absorption maximum of 415 nm(More)
Many of the spectroscopic features and photophysical properties of carotenoids are explained using a three-state model in which the strong visible absorption of the molecules is associated with an S0 (1(1)Ag-) --> S2 (1(1)Bu+) transition, and the lowest lying singlet state, S1 (2(1)Ag-), is a state into which absorption from the ground state is forbidden by(More)