Evidence for charge-controlled conformational changes in the photocycle of bacteriorhodopsin.

摘要: Abstract The existence of two different M-state structures in the photocycle bacteriorhodopsin mutant ASP38ARG was proved. At pH 6.7 (0 to −6°C) a spectroscopic M intermediate (M 1 ) that does not differ significantly its tertiary structure from light-adapted ground state accumulates under illumination. pH>9 another 2 ), characterized by additional pronounced changes Fourier transform infrared difference spectrum region amide I and II bands, accumulates. trapped at 9.6 displays same x-ray diffraction intensities continuous illumination as previously described for experiments with ASP96ASN. These observations indicate this altered charge distribution neutral controls structural seem be necessary proton translocation.