Photolysis of rhodopsin results in deprotonation of its retinal Schiff's base prior to formation of metarhodopsin II.
Absorption changes following photolysis of bovine rhodopsin in mildly sonicated membrane suspensions are monitored at 25 degrees C. Difference spectra collected at 17 times between 1 microsecond and 75 ms following excitation are analyzed globally using singular value decomposition and non-linear least-squares fitting techniques. The results are not consistent with the simple scheme: Lumirhodopsin-->Metarhodopsin I<-->Metarhodopsin II, but indicate that an intermediate with a deprotonated Schiff's base is formed nearly simultaneously with metarhodopsin I upon the decay of Lumirhodopsin.
Thorgeirsson
T E
TE
Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064.
Lewis
J W
JW
Wallace-Williams
S E
SE
Kliger
D S
DS
D000818:Animals; D002417:Cattle; D066298:In Vitro Techniques; D010782:Photolysis; D011522:Protons; D012172:Retinaldehyde / Q000737:chemistry; D012243:Rhodopsin / Q000031:analogs & derivatives / Q000737:chemistry / Q000528:radiation effects*; D012545:Schiff Bases / Q000737:chemistry
D011522:Protons; D012545:Schiff Bases; C013110:metarhodopsins; D012243:Rhodopsin; D012172:Retinaldehyde