Labrude P, Chaillot B, Vigneron C
J Pharm Pharmacol. 1987 May;39(5):344-8. doi: 10.1111/j.2042-7158.1987.tb03396.x.
Formation of methaemoglobin during freeze-drying of oxyhaemoglobin raises the question of the cause and mechanism of the oxidation. Haemoglobin with or without lyoprotector (250 mM glucose or amino acid salt) has been subjected to freeze drying changes in either or both of two constraints--vacuum and rise in temperature. A rise in temperature from -40 to +10 degrees C had no substantial denaturing effect on haemoglobin whether protected or not. Maintenance of a vacuum over frozen haemoglobin for 18 h often produced subtotal desiccation. Unprotected haemoglobin was partially oxidized (39% MetHb) whereas protected haemoglobin was not (less than 4% MetHb). Haemoglobin was also dried by rapid dehydration of thin films in a stream of air at room temperature (20 degrees C). The methaemoglobin content was then 43% whereas the amino acid salt or glucose limited it at 4 and 7%, respectively. Haemoglobin is oxidized, therefore, only because of the removal of water. Protectors, not specific in structure and action, probably work by holding or reinforcing the critical number of hydration layers around haemoglobin.
氧合血红蛋白冻干过程中高铁血红蛋白的形成引发了氧化原因及机制的问题。含有或不含冻干保护剂（250 mM葡萄糖或氨基酸盐）的血红蛋白在真空和温度升高这两种限制条件中的一种或两种下进行冻干处理。温度从-40℃升至+10℃，无论有无保护剂，对血红蛋白都没有实质性的变性作用。在冷冻的血红蛋白上维持真空18小时常常会导致近乎完全干燥。未加保护剂的血红蛋白部分被氧化（39%高铁血红蛋白），而加了保护剂的血红蛋白则未被氧化（低于4%高铁血红蛋白）。血红蛋白也通过在室温（20℃）的气流中快速干燥薄膜来干燥。此时高铁血红蛋白含量为43%，而氨基酸盐或葡萄糖分别将其限制在4%和7%。因此，血红蛋白被氧化仅仅是因为水分的去除。保护剂在结构和作用上并无特异性，可能是通过保持或加强血红蛋白周围关键数量的水化层来发挥作用。
