Difference spectra of late intermediates of the bacteriorhodopsin photocycle

Journal Article · Sat Dec 31 23:00:00 EST 1988 · [Formerly used by DOE/TIC for titles for which valid CODEN was not available. Now invalid] 92-DEC-15; (Country unknown/Code not available)

OSTI ID:6969279

Govindjee, R; Dancshazy, Zs; Ebrey, T G ^[1]

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1. Univ. of Illinois, Urbana (United States)

The flash-induced difference absorbance spectra of bacteriorhodopsin (BR) were measured at various times after an actinic flash using a diode array spectrophotometer (300-700 nm). Difference spectra for three late bacteriorhodopsin photocycle intermediates M[sup fast] (M[sup f]), M[sup slow] (M[sup s]) and R are reported. The main distinguishing features of the 3 difference spectra at pH = 10.5 and 5C are as follows: M[sup f]: [triangle]A[sub max] = 412 nm, a shoulder at 436 nm, no absorbance change at 350 nm, [triangle]A[sub min] = 565 nm, [triangle]A412/[triangle]A565 = 0.8-0.9. M[sup s]: [triangle]A[sub max] = 412 nm, a shoulder at 386 nm, [triangle]A[sub min] = 570-575 nm, [triangle]A412/[triangle]A575 = 0.6. R: [triangle]A[sub max] = 336 and 350 nm (double peak ), minor peaks at 386 and 412 nms, [triangle]A[sub min] = 585-590 nm; [triangle]A350/[triangle]A585 = 0.2. The t[sub 1/2] of M[sup f], M[sup s] and R and the relative weights of BR570 recovered with these rates are: 1 sec (50%), 3-5 sec (25%) and 35 sec (25%) respectively. These spectral features can also be seen at pH = 7, [minus]16C, and at pH = 9-10.5, 20C. Based on some assumptions, the absorption maximum of R was calculated to be at ca. 550 nm. The extinction coefficient of R is approximately 70% that of light-adapted BR.

• OSTI ID: 6969279
• Journal Information: [Formerly used by DOE/TIC for titles for which valid CODEN was not available. Now invalid] 92-DEC-15; (Country unknown/Code not available), Journal Name: [Formerly used by DOE/TIC for titles for which valid CODEN was not available. Now invalid] 92-DEC-15; (Country unknown/Code not available) Vol. 1057; ISSN ZZZZZV
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTRA
CHEMICAL REACTIONS
MEMBRANES
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHOTOSYNTHETIC BACTERIA
PHOTOSYNTHETIC MEMBRANES
PHOTOSYNTHETIC REACTION CENTERS
PIGMENTS
PROTEINS
RHODOPSIN
SPECTRA
SPECTROPHOTOMETRY
SYNTHESIS