Metarhodopsin III formation and decay kinetics: comparison of bovine and human rhodopsin.
Absorbance spectra were recorded at various times after photolysis of hypotonically washed membrane suspensions of human and bovine rhodopsin (pH 7 or 8, T = 20 or 37 degrees C). Global data analysis showed that at 20 degrees C, metarhodopsin III formation was the only process occurring from 1 to 30 min following photolysis. At pH 8, a significant amount of human metarhodopsin I was present before metarhodopsin III formed. At 37 degrees C, two decay processes were seen, formation of metarhodopsin III (lifetime 113 +/- 3 sec bovine, 93 +/- 2 sec human) and formation of a species with the properties of n-retinylidine opsin (lifetime 900 +/- 150 sec bovine, 2000 +/- 350 sec human). A larger fraction of human rhodopsin (approximately 50%) is converted to metarhodopsin III than is the case for bovine rhodopsin (approximately 35%).
Lewis
J W
JW
Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064, USA.
van Kuijk
F J
FJ
Carruthers
J A
JA
Kliger
D S
DS
D000818:Animals; D002417:Cattle; D006801:Humans; D010782:Photolysis; D012243:Rhodopsin / Q000031:analogs & derivatives* / Q000378:metabolism*; D013057:Spectrum Analysis
C013110:metarhodopsins; D012243:Rhodopsin