L-gulonolactone Oxidase
-gulonolactone oxidase (EC 1.1.3.8) is an enzyme that that produces vitamin C, but that is non-functional in humans and some other primates. It catalyzes the reaction of -glucuronolactone (also known as -gulono-1,4-lactone) with oxygen to -xylo-hex-3-gulonolactone and hydrogen peroxide. It uses FAD as a cofactor. The -xylo-hex-3-gulonolactone (2-keto-gulono-gamma-lactone) is able to spontaneously convert to hexuronic acid (ascorbic acid), without enzymatic action.
Read more about L-gulonolactone Oxidase: Gulonolactone Oxidase Deficiency, Consequences of Loss, Animal Models