Retinyl ester hydrolase and the visual cycle in the chicken eye

J. J. Bustamante, S. Ziari, R. D. Ramirez, A. T C Tsin

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

The ability of chicken retina and retinal pigment epithelium (RPE) membrane to hydrolyze vitamin A esters ([9,10-3H]all-trans- and 11-cis- retinyl palmitate) was studied. Hydrolytic activity within the retina was optimal at acidic pH of 5.0, whereas in the RPE significant hydrolytic activity was exhibited over a broad range of hydrogen ion concentrations. The highest rate of hydrolysis was associated with the all-trans-isomer and located within retina and RPE membranes [the apparent maximal velocity (V(max)) and Michaelis-Menten constant (K(m)) were 770 pmol · min · -1 · mg-1 and 45 μM and 300 pmol · min · -1 · mg-1 and 3.6 μM, respectively]. Retinyl ester hydrolase activities for 11-cis-retinyl palmitate in the retina and RPE were correspondingly lower (apparent V(max) of 204 pmol · min · -1 · mg-1 and K(m) of 18.5 μM in the retina; apparent V(max) of 131 pmol · min · -1 · mg-1 and K(m) of 4 μM in the RPE). Together with results from other laboratories, results from the present study suggest that chicken retina contains important enzymes to complete the visual cycle.

Original languageEnglish (US)
Pages (from-to)R1346-R1350
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume269
Issue number6 38-6
DOIs
StatePublished - 1995

Keywords

  • enzymes
  • retina
  • retinyl pigment epithelium
  • vitamin A

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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