Two progressive substrates of the M-intermediate can be identified in glucose-embedded, wild-type bacteriorhodopsin.
AUTOR(ES)
Vonck, J
RESUMO
Glucose-embedded bacteriorhodopsin shows M-intermediates with different Amide I infrared bands when samples are illuminated at 240 or 260 K, in contrast with fully hydrated samples where a single M-intermediate is formed at all temperatures. In hydrated, but not in glucose-embedded specimens, the N intermediate is formed together with M at 260 K. Both Fourier transform infrared and electron diffraction data from glucose-embedded bacteriorhodopsin suggest that at 260 K a mixture is formed of the M-state that is trapped at 240 K, and a different M-intermediate (MN) that is also formed by mutant forms of bacteriorhodopsin that lack a carboxyl group at the 96 position, necessary for the M to N transition. The fact that an MN species is trapped in glucose-embedded, wild-type bacteriorhodopsin suggests that the glucose samples lack functionally important water molecules that are needed for the proton transfer aspartate 96 to the Schiff base (and, thus, to form the N-intermediate); thus, aspartate 96 is rendered ineffective as a proton donor.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1225472Documentos Relacionados
- The bacteriorhodopsin photocycle: direct structural study of two substrates of the M-intermediate.
- Overexpression of Wild-Type Murine Tau Results in Progressive Tauopathy and Neurodegeneration
- Molecular dynamics study of the M412 intermediate of bacteriorhodopsin.
- Defective Tobamovirus Movement Protein Lacking Wild-Type Phosphorylation Sites Can Be Complemented by Substitutions Found in Revertants
- Wild-type p53 can down-modulate the activity of various promoters.