Izutsu K, Yoshioka S, Terao T
National Institute of Health Sciences, Tokyo, Japan.
Chem Pharm Bull (Tokyo). 1994 Jan;42(1):5-8. doi: 10.1248/cpb.42.5.
The stabilizing effect of mannitol during the freeze-drying of proteins was studied using L-lactate dehydrogenase (LDH, rabbit muscle), beta-galactosidase (Escherichia coli) and L-asparaginase (Erwinia chrysanthemi) as model proteins. Crystallization of mannitol was studied by powder X-ray diffraction and differential scanning calorimetry (DSC), in relation to the stabilizing effect. All the enzymes were protected concentration-dependently by amorphous mannitol, but the stabilizing effect was decreased with an increase in mannitol crystallinity. The heat-treatment of frozen solutions above crystallization temperature prior to drying enhanced mannitol crystallization and LDH inactivation. The importance of maintaining excipients in an amorphous state during freeze-drying, previously reported for Aspergillus oryzae beta-galactosidase (K. Izutsu et al., Pharm. Res., 10, 1233 (1993)), was confirmed using three different enzymes.
以L-乳酸脱氢酶（LDH，兔肌肉）、β-半乳糖苷酶（大肠杆菌）和L-天冬酰胺酶（菊欧文氏菌）作为模型蛋白，研究了甘露醇在蛋白质冷冻干燥过程中的稳定作用。通过粉末X射线衍射和差示扫描量热法（DSC）研究了甘露醇的结晶情况及其与稳定作用的关系。所有酶均受到无定形甘露醇的浓度依赖性保护，但随着甘露醇结晶度的增加，稳定作用减弱。干燥前在高于结晶温度下对冷冻溶液进行热处理会增强甘露醇的结晶和LDH的失活。使用三种不同的酶证实了冻干过程中保持辅料处于无定形状态的重要性，此前这一情况已在米曲霉β-半乳糖苷酶中得到报道（K. Izutsu等人，《药物研究》，10，1233（1993））。
