Tyrosine and carboxyl protonation changes in the bacteriorhodopsin photocycle. 2. Tyrosine-26 and -64

Journal Article · Tue Oct 20 00:00:00 EDT 1987 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00395a021· OSTI ID:5532174

Roepe, P; Scherrer, P; Ahl, P L; Gupta, S K.D.; Bogomolni, R A; Herzfeld, J; Rothschild, K J

Low-temperature Fourier transform infrared (FTIR) and UV difference spectroscopies combined with selective tyrosine nitration and tyrosine isotopic labeling have been used to investigate the participation of tyrosines-26 and -64 in the bacteriorhodopsin (bR) photocycle. Nitration of Tyr-26 has no detectable effect on the FTIR or UV difference spectra of the BR/sub 570/ ..-->.. K/sub 630/ or BR/sub 570/ ..-->.. M/sub 412/ transitions. In contrast, nitration of Tyr-64 causes changes in both the FTIR and UV spectra of these transitions. However, this nitration does not alter tyrosine peaks in the FTIR difference spectra which have previously been associated with the protonation of a tyrosinate by K/sub 630/ and the deprotonation of a tyrosine by M/sub 412/. Instead, Tyr-64 nitration appears to affect other tyrosine peaks. These results and changes in UV difference spectra upon Tyr-64 nitration are consistent with the deprotonation of Tyr-64 by M/sub 412/ as concluded previously. Effects on chromophore vibrations caused by Tyr-64 nitration are unaltered upon reducing the nitrotyrosine to aminotyrosine with sodium dithionite. Finally, nitro-Tyr-64 causes a shift in the frequency of a positive peak at 1739 cm/sup -1/ in the BR/sub 570/ ..-->.. M/sub 412/ FTIR difference spectrum which reflects the protonation of a carboxyl-containing residue. The shift does not occur for samples containing amino-Tyr-64. These data suggest that Tyr-64 may interact with this carboxyl group.

• Research Organization: Boston Univ., MA
• OSTI ID: 5532174
• Journal Information: Biochemistry; (United States), Vol. 26:21
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
59 BASIC BIOLOGICAL SCIENCES
RHODOPSIN
INFRARED SPECTRA
ULTRAVIOLET SPECTRA
TYROSINE
PHOTOCHEMISTRY
BIOCHEMISTRY
CHEMICAL SHIFT
DEUTERIUM COMPOUNDS
PHOTOSYNTHETIC BACTERIA
PHOTOSYNTHETIC MEMBRANES
AMINO ACIDS
CARBOXYLIC ACIDS
CHEMISTRY
HYDROGEN COMPOUNDS
HYDROXY ACIDS
MEMBRANES
ORGANIC ACIDS
ORGANIC COMPOUNDS
PIGMENTS
PROTEINS
SPECTRA
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