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Biogenesis of the purple membrane of Halobacterium halobium (1977)

Danon, A. ; Brith-Lindner, M. ; Caplan, S. R.

Springer

European biophysics journal 3 (1977), S. 1-17

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ISSN: 1432-1017

Keywords: Purple membrane ; Bacteriorhodopsin ; Biosynthesis ; Retinal ; Nicotine

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Physics

Notes: Abstract A protein closely resembling the purple membrane protein pre-exists in the cell membrane of H. halobium prior to the appearance of functional bacteriorhodopsin. It is associated with a differentiated membranous structure which has been isolated on a sucrose gradient and appears to be a precursor of the purple membrane. The identity of the precursor protein as a form of the purple membrane protein was established in different ways: (1) The cell proteins were labelled in vivo with 14C-proline during dark aerobic growth, the label was “chased”, and the cells transferred to the illuminated near-anaerobic conditions under which purple membrane is optimally synthesised (induction conditions). Cell lysates were fractionated on sucrose gradients at different times after induction. Label first found in the precursor fraction appeared within 24 h in the purple membrane fraction. (2) SDS-urea-acrylamide gel electrophoresis of the purple membrane protein and the precursor showed only one protein band whose migration coincided with that of the purple membrane band. (3) The amino-acid analysis of the purified precursor was very similar to that of the purple membrane. The absorption spectrum of the precursor showed little of the characteristic absorption of bacteriorhodopsin at 570 nm. A major band appears at 412 nm, the exact nature of which is not known. The difference spectrum (reduced versus oxidised) of a purified fraction showed only traces of cytochrome. Thin-layer chromatography of an acetone-soluble lipid extract indicated the presence of retinal and Β-carotene. Cells grown in the presence of nicotine did not develop purple membrane after induction: the species absorbing at 412 nm was much less abundant than in non-inhibited cells, but a new fraction was present with a sharp peak at 345 nm consisting mainly of lycopene.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00536449

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Raman optical activity of enantiomorphic single crystals (1995)

Lindner, M. ; Schrader, B. ; Hecht, L.

Chichester [u.a.] : Wiley-Blackwell

Journal of Raman Spectroscopy 26 (1995), S. 877-882

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ISSN: 0377-0486

Keywords: Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: Conventional Raman and incident circular polarization Raman optical activity (ROA) spectra are presented for the lattice vibrations of enantiomorphic pairs of optically active cubic crystals NaBrO3 and NaCIO3 in depolarized right-angle scattering (65-145 cm-1) and unpolarized backscattering (55-200 cm-1). Since enantiomorphic cubic crystals are also piezoelectric owing to the lack of a centre of inversion, the degeneracy of their triply degenerate polar (infrared and Raman active) F phonons is partially lifted because of long-range dipole-dipole interactions. Therefore, non-degenerate longitudinal and doubly degenerate transverse optical phonons can be separately observed in the ROA spectra.

Additional Material: 6 Ill.