The metabolism of d-glyceraldehyde by the lens

1. The metabolism of d-glyceraldehyde by the lens was examined. 2. When low concentrations of d-[U−14C]glyceraldehyde were incubated with lens extracts there was no incorporation of the label into protein; more than two-thirds of the labelled metabolites consisted of glyceric acid and glycerol, their relative proportions depending on the species. Lactic acid, a phosphate, glutathione–glyceraldehyde compounds and a neutral compound were also formed. 3. When high concentrations of d-[U−14C]glyceraldehyde were incubated with lens, extensive incorporation of the label into protein occurred and the protein became yellow–brown. This coloured protein did not exhibit the fluorescent properties shown by the brown proteins of human cataractous senile lens, or of naphthaquinone-treated lens. 4. Evidence that d-glyceraldehyde is formed by the lens was sought but not found.