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Vis Neurosci. 1992 Apr;8(4):329-36.

Retinoids in the lateral eye of Limulus: evidence for a retinal photoisomerase.

Author information

1
Department of Biology, Yale University, New Haven.

Abstract

The lateral eyes of the horseshoe crab Limulus contain about 80 pmoles of retinal, 30 pmoles of retinol, and 4 pmoles of retinyl esters. More all-trans than 11-cis isomer was found in each category of retinoid. No consistent changes were observed in the amounts of retinal, retinol, or retinyl esters as a function of time of day. No 3,4-dehydro- nor hydroxyretinoids were found. Aqueous extracts of the eye support the stereospecific formation of 11-cis retinal from all-trans retinal when irradiated with light. The reaction requires a protein that is apparently recognized by polyclonal antibodies raised against the retinal photoisomerase extracted from honeybee eyes. The isomerase is able to use as substrate either endogenous all-trans retinal in the extract of retinal supplied in vesicles of phospholipid. The spectral efficiency of this isomerization has lambda max at 550 nm, but the spectrum appears too narrow compared with the absorbance spectrum of retinoid-binding proteins, probably because of inadequate correction for nonspecific isomerization at short wavelengths.

PMID:
1562568
DOI:
10.1017/s095252380000506x
[Indexed for MEDLINE]

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