PURPOSE: To crystallize the titled substance important as a measuring factor in enzyme analysis for measuring enzyme activity and substrate concentration simply in high yield, by adjusting a noncrystalline substance into an aqueous solution having a specific concentration, followed by cooling it to a specified temperature.
CONSTITUTION: For example, a noncrystalline β-nicotinamide-adenine-dinucleotide (NAD) is first dissolved in water, and it is purified by removing impurities preferably with an acetate type high porous weakly basic anion exchange resin. This aqueous solution of NAD is adjusted to a concentration of 20W60(w/v)%, preferably 40W50 (w/v)% cooled, to 0W20°C, preferably 2W8°C, and NAD is crystallized and precipitated.
EFFECT: Since it is obtained in pure state, preservation and transportation at low temperature are not required.
KOBAYASHI YUKIHARU
YANO MASAO
