Visual pigments and bacteriorhodopsin: A resonance Raman study.
Item
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Title
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Visual pigments and bacteriorhodopsin: A resonance Raman study.
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Identifier
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AAI9000728
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identifier
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9000728
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Creator
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Rath, Parshuram.
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Contributor
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Adviser: Robert H. Callender
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Date
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1989
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biophysics, General
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Abstract
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In an effort to achieve better understanding of the mechanism of visual transduction in invertebrates, we have studied two visual pigments: the ultraviolet absorbing invertebrate visual pigment of owlfly (Ascalaphus macaronius) and the visible absorbing pigment of octopus (Paroctopus deflini). Studies on the owlfly pigment suggest that a protonated chromophore is essential for vision to occur and that both the vertebrates and invertebrates share a common mechanism of visual transduction. We have worked towards resolving the observed differences in the low frequency HOOP region of octopus and bovine bathorhodopsins. Resonance Raman studies of C{dollar}\sb{10}{dollar}-D and C{dollar}\sb{12}{dollar}-D retinal regenerated octopus visual pigments suggest that the location of a negatively charged protein residue near C{dollar}\sb{12}{dollar} of octopus bathorhodopsin chromophore is unlikely.;We have also studied another light transducing retinal pigment, bacteriorhodopsin. We have regenerated bacteriorhodopsin from opsin and all-trans retinal and an intermediate of regeneration was studied. Results suggest that the shift in color of the retinal from 380 nm to 570 nm (in the reconstituted pigment) is achieved through several steps. An analogue of bacteriorhodopsin, 13-bromo-bR, was also studied. We have looked into the various intermediates of its photocycle. Our data suggest that although the thermal isomerization of this chromophore is hindered, its photoisomerization is quite efficient. We have also looked into the possible existence of different pH dependent forms of bacteriorhodopsin. Our Raman data are in disagreement with such hypothesis.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
