STUDIES ON THE RIBOFLAVIN-BINDING CAPACITY OF THE RAT LENS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 53  (3) , 243-250
Abstract
Riboflavin-binding in the rat lens was the same at 4.degree. C and 37.degree. C; there was a saturation curve when 14C-riboflavin was the substrate; there was an ATP-dependent increase of binding; and EGTA [ethylene glycol bis(.beta.-aminoethyl ether)-N,N,N'',N''-tetraacetic acid] and PCMB [p-chloromercuribenzoate] did not affect riboflavin binding while it was decreased upon protease digestion and upon the addition of heavy metal compounds. Furthermore, binding was lower in the lenses of rats which had been fed a B2-deficient diet for 8 wk than in animals receiving this diet for 4 wk. When 14C-B2 butyrate rather than 14C-riboflavin was the substrate, binding was considerably higher in the lens homogenate and the single whole lens. Partial purification of riboflavin-binding protein using flavinyl agar-bead affinity chromatography confirmed the presence of a trace amount of riboflavin-binding protein in bovine lens. Changes in the riboflavin-binding capacity of the lens may play a role in the regulation of absorption, transport and metabolism of riboflavin in the lens associated with the synthesis of ester forms of riboflavin.