Preparation and properties of soluble-insoluble nicotinamide coenzymes.

A soluble-insoluble form of nicotinamide adenine dinucleotide (NAD+), which can be rendered either soluble or insoluble by simply adjusting the pH, has been prepared by covalently coupling NAD to alginic acid using 1,2,7,8-diepoxyoctane. The NAD bound to the alginic acid showed the coenzymic function in the soluble state and could be collected for further use as precipitate by lowering the pH to below 3. Coupling soluble-insoluble coenzymes with insolubilized apoenzymes is possible in fluidized and fixed-bed reactors.