School of Pharmacy, University of Connecticut, Storrs, Connecticut 06269-3092, USA.
Pharm Res. 2011 Dec;28(12):3237-47. doi: 10.1007/s11095-011-0512-8. Epub 2011 Jun 25.
To relate NMR relaxation times to instability-related molecular motions of freeze-dried protein formulations and to examine the effect of sugars on these motions.
Rotating-frame spin-lattice relaxation time (T(1ρ)) was determined for both protein and sugar carbons in freeze-dried lysozyme-sugar (trehalose, sucrose and isomaltose) formulations using solid-state (13)C NMR.
The temperature dependence of T(1ρ) for the lysozyme carbonyl carbons in lysozyme with and without sugars was describable with a model that includes two different types of molecular motion with different correlation times (τ(c)) for the carbon with each τ(c) showing Arrhenius temperature dependence. Both relaxation modes have much smaller relaxation time constant (τ(c)) and temperature coefficient (Ea) than structural relaxation and may be classified as β-relaxation and γ-relaxation. The τ(c) and Ea for γ-relaxation were not affected by sugars, but those for β-relaxation were increased by sucrose, changed little by trehalose, and decreased by isomaltose, suggesting that the β-mobility of the lysozyme carbonyl carbons is decreased by sucrose and increased by isomaltose.
T(1ρ) determined for the lysozyme carbonyl carbons can reflect the effect of sugars on molecular mobility in lysozyme. However, interpretation of relaxation time data is complex and may demand data over an extended temperature range.
将 NMR 弛豫时间与冷冻干燥蛋白质制剂中与不稳定性相关的分子运动相关联，并研究糖对这些运动的影响。
使用固态（13）C NMR 测定冷冻干燥溶菌酶-糖（海藻糖、蔗糖和异麦芽糖）制剂中蛋白质和糖碳的旋转框架自旋晶格弛豫时间（T（1ρ））。
有糖和无糖溶菌酶羰基碳的 T（1ρ）随温度的变化可以用一个模型来描述，该模型包括两种不同类型的分子运动，每种分子运动的相关时间（τ（c））不同，τ（c）表现出Arrhenius 温度依赖性。两种弛豫模式的弛豫时间常数（τ（c））和温度系数（Ea）都比结构弛豫小得多，可归类为β-弛豫和γ-弛豫。γ-弛豫的τ（c）和 Ea不受糖的影响，但β-弛豫的τ（c）和 Ea受蔗糖的影响，受海藻糖的影响较小，受异麦芽糖的影响较小，这表明蔗糖降低了溶菌酶羰基碳的β-流动性，而异麦芽糖增加了溶菌酶羰基碳的β-流动性。
溶菌酶羰基碳的 T（1ρ）可以反映糖对溶菌酶中分子流动性的影响。然而，弛豫时间数据的解释很复杂，可能需要在较宽的温度范围内进行数据。
