The bacteriorhodopsin photocycle: direct structural study of two substrates of the M-intermediate.
AUTOR(ES)
Han, B G
RESUMO
Changes in protein structure that occur during the formation of the M photointermediate of bacteriorhodopsin can be directly visualized by electron diffraction techniques. A modified preparation technique for glucose-embedded crystals was employed to ensure sufficient hydration of the crystals, which was needed for the formation of the M intermediate at low temperature. Samples containing a high percentage of the M intermediate were trapped by rapidly cooling the crystals with liquid nitrogen after illumination with filtered green light at 240 and 260 K, respectively. Difference Fourier projection maps are presented for the M intermediates formed at these two temperatures. The diffraction data clearly show that statistically significant structural changes occur upon formation of the M intermediate at 240 K and then further upon formation of the second specimen that is produced at 260 K.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1225473Documentos Relacionados
- Two progressive substrates of the M-intermediate can be identified in glucose-embedded, wild-type bacteriorhodopsin.
- Chromophore motion during the bacteriorhodopsin photocycle: polarized absorption spectroscopy of bacteriorhodopsin and its M-state in bacteriorhodopsin crystals.
- Evidence for the first phase of the reprotonation switch of bacteriorhodopsin from time-resolved photovoltage and flash photolysis experiments on the photoreversal of the M-intermediate.
- Primary step in the bacteriorhodopsin photocycle: photochemistry or excitation transfer?
- Protein dynamics in the bacteriorhodopsin photocycle: submillisecond Fourier transform infrared spectra of the L, M, and N photointermediates.