Miller D P, Anderson R E, de Pablo J J
Department of Chemical Engineering, University of Wisconsin-Madison 53706, USA.
Pharm Res. 1998 Aug;15(8):1215-21. doi: 10.1023/a:1011987707515.
The purpose of this work was to investigate the effects of trehalose and trehalose/sodium tetraborate mixtures on recovery of lactate dehydrogenase (LDH) activity following freeze-thawing and centrifugal vacuum-drying/rehydration. The storage stability of LDH under conditions of either high relative humidity or high temperature was also studied.
LDH was prepared in buffered aqueous formulations containing trehalose alone and trehalose/"borate" mixtures. Enzymatic activity was measured immediately following freeze-thawing and vacuum-drying/rehydration processes, and also after vacuum-dried formulations were stored in either high humidity or high temperature environments. Also, glass transition temperatures (Tg) were measured for both freeze-dried and vacuum-dried formulations.
The Tg values of freeze-dried trehalose/borate mixtures are considerably higher than that of trehalose alone. Freezing and vacuum-drying LDH in the presence of 300 mM trehalose resulted in the recovery of 80% and 65% of the original activity, respectively. For vacuum-dried mixtures, boron concentrations below 1.2 mole boron/ mole trehalose had no effect on recovered LDH. After several weeks storage in either humid (100% relative humidity) or warm (45 degrees C) environments, vacuum-dried formulations that included trehalose and borate showed greater enzymatic activities than those prepared with trehalose alone. We attribute this stability to the formation of a chemical complex between trehalose and borate.
The high Tg values of trehalose/borate mixtures offer several advantages over the use of trehalose alone. Most notable is the storage stability under conditions of high temperature and high relative humidity. In these cases, formulations that contain trehalose and borate are superior to those containing trehalose alone. These results have practical implications for long-term storage of biological materials.
本研究旨在探讨海藻糖及海藻糖/四硼酸钠混合物对乳酸脱氢酶（LDH）冻融及离心真空干燥/复水后活性恢复的影响。同时还研究了LDH在高相对湿度或高温条件下的储存稳定性。
将LDH制备于仅含海藻糖及海藻糖/“硼酸盐”混合物的缓冲水性制剂中。在冻融及真空干燥/复水过程后，以及真空干燥制剂在高湿度或高温环境中储存后，立即测定酶活性。此外，还测定了冻干和真空干燥制剂的玻璃化转变温度（Tg）。
冻干海藻糖/硼酸盐混合物的Tg值显著高于单独的海藻糖。在300 mM海藻糖存在下冷冻和真空干燥LDH，其活性分别恢复至原来的80%和65%。对于真空干燥的混合物，硼浓度低于1.2摩尔硼/摩尔海藻糖对恢复的LDH没有影响。在潮湿（100%相对湿度）或温暖（45℃）环境中储存数周后，包含海藻糖和硼酸盐的真空干燥制剂比仅用海藻糖制备的制剂显示出更高的酶活性。我们将这种稳定性归因于海藻糖和硼酸盐之间形成的化学复合物。
海藻糖/硼酸盐混合物的高Tg值比单独使用海藻糖具有多个优势。最显著的是在高温和高相对湿度条件下的储存稳定性。在这些情况下，含有海藻糖和硼酸盐的制剂优于仅含海藻糖的制剂。这些结果对生物材料的长期储存具有实际意义。
