Crystalline solids A to E of biopterin are distinguished from each other by diffraction angle in an X-ray powder diffraction pattern measured using Cu—Kα radiation. The crystalline solid A is characterized by strong peak at 4.6° and peaks at 13.6°, 18.1° and 27.5°; the crystalline solid B is characterized by strong peak at 4.85° and peaks at 2.4°, 13.2°, 18.1° and 27.3°; the crystalline solid C is characterized by strong peak at 5.35° and peaks at 10.8°, 21.9° and 27.3°; the crystalline solid D is characterized by strong peak at 5.1° and peaks at 2.6°, 9.2°, 13.4°, 15.4°, 18.3°, 21.8° and 27.3°; and the crystalline solid E is characterized by strong peaks at 4.5° and 5.8°, and peaks at 10.6°, 15.6°, 20.0°, 20.7°, 23.8° and 27.3°.
生物酶素的晶体固体A至E通过使用Cu—Kα辐射测量的X射线粉末衍射图案中的衍射角度来区分。晶体固体A的特征是在4.6°处有强峰和在13.6°、18.1°和27.5°处有峰;晶体固体B的特征是在4.85°处有强峰和在2.4°、13.2°、18.1°和27.3°处有峰;晶体固体C的特征是在5.35°处有强峰和在10.8°、21.9°和27.3°处有峰;晶体固体D的特征是在5.1°处有强峰和在2.6°、9.2°、13.4°、15.4°、18.3°、21.8°和27.3°处有峰;晶体固体E的特征是在4.5°和5.8°处有强峰,以及在10.6°、15.6°、20.0°、20.7°、23.8°和27.3°处有峰。