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J Gen Physiol. 1963 Nov 1; 47(2): 215–240.
PMCID: PMC2195338

Tautomeric Forms of Metarhodopsin


Light isomerizes the chromophore of rhodopsin, 11-cis retinal (formerly retinene), to the all-trans configuration. This introduces a succession of unstable intermediates—pre-lumirhodopsin, lumirhodopsin, metarhodopsin —in which all-trans retinal is still attached to the chromophoric site on opsin. Finally, retinal is hydrolyzed from opsin. The present experiments show that metarhodopsin exists in two tautomeric forms, metarhodopsins I and II, with λmax 478 and 380 mµ. Metarhodopsin I appears first, then enters into equilibrium with metarhodopsin II. In this equilibrium, the proportion of metarhodopsin II is favored by higher temperature or pH, neutral salts, and glycerol. The change from metarhodopsin I to II involves the binding of a proton by a group with pK 6.4 (imidazole?), and a large increase of entropy. Metarhodopsin II has been confused earlier with the final mixture of all-trans retinal and opsin (λmax 387 mµ), which it resembles in spectrum. These two products are, however, readily distinguished experimentally.

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Selected References

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  • BALL S, COLLINS FD, et al. Studies in vitamin A; reactions of retinene1 with amino compounds. Biochem J. 1949;45(3):304–307. [PMC free article] [PubMed]
  • BROWN PK, BROWN PS. Visual pigments of the octopus and cuttlefish. Nature. 1958 Nov 8;182(4645):1288–1290. [PubMed]
  • COLLINS FD. Rhodopsin and indicator yellow. Nature. 1953 Mar 14;171(4350):469–471. [PubMed]
  • GRELLMANN KH, LIVINGSTON R, PRATT D. A flashphotolytic investigation of rhodopsin at low temperatures. Nature. 1962 Mar 31;193:1258–1260. [PubMed]
  • HUBBARD R. The thermal stability of rhodopsin and opsin. J Gen Physiol. 1958 Nov 20;42(2):259–280. [PMC free article] [PubMed]
  • Hubbard R, Kropf A. THE ACTION OF LIGHT ON RHODOPSIN. Proc Natl Acad Sci U S A. 1958 Feb;44(2):130–139. [PMC free article] [PubMed]
  • HUBBARD R, ST GEORGE RC. The rhodopsin system of the squid. J Gen Physiol. 1958 Jan 20;41(3):501–528. [PMC free article] [PubMed]
  • HVIDT A, LINDERSTROM-LANG K. Exchange of deuterium and 18O between water and other substances. III. Deuterium exchange of short peptides, Sanger's A-chain and insulin. C R Trav Lab Carlsberg Chim. 1955;29(22-23):385–402. [PubMed]
  • KROPF A, HUBBARD R. The mechanism of bleaching rhodopsin. Ann N Y Acad Sci. 1959 Nov 12;74(2):266–280. [PubMed]
  • Lythgoe RJ, Quilliam JP. The relation of transient orange to visual purple and indicator yellow. J Physiol. 1938 Dec 14;94(3):399–410. [PMC free article] [PubMed]
  • MORTON RA, PITT GA. Studies on rhodopsin. IX. pH and the hydrolysis of indicator yellow. Biochem J. 1955 Jan;59(1):128–134. [PMC free article] [PubMed]
  • PITT GA, COLLINS FD, MORTON RA, STOK P. Studies on rhodopsin. VIII. Retinylidenemethylamine, an indicator yellow analogue. Biochem J. 1955 Jan;59(1):122–128. [PMC free article] [PubMed]
  • RADDING CM, WALD G. Acid-base properties of rhodopsin and opsin. J Gen Physiol. 1956 Jul 20;39(6):909–922. [PMC free article] [PubMed]
  • WALD G, BROWN PK. The role of sulfhydryl groups in the bleaching and synthesis of rhodopsin. J Gen Physiol. 1952 May;35(5):797–821. [PMC free article] [PubMed]
  • WALD G, DURELL J, ST GEORGE CC. The light reaction in the bleaching of rhodopsin. Science. 1950 Feb 17;111(2877):179–181. [PubMed]
  • WULFF VJ, ADAMS RG, LINSCHITZ H, ABRAHAMSON EW. Effect of flash illumination on rhodopsin in solution. Ann N Y Acad Sci. 1959 Nov 12;74(2):281–290. [PubMed]
  • YOSHIZAWA T, WALD G. Pre-lumirhodopsin and the bleaching of visual pigments. Nature. 1963 Mar 30;197:1279–1286. [PubMed]

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