Boggs J M, Rangaraj G, Moscarello M A, Koshy K M
Biochim Biophys Acta. 1985 Jun 27;816(2):208-20. doi: 10.1016/0005-2736(85)90488-2.
The effect of myelin basic protein on the myelin lipid cerebroside sulfate was studied by differential scanning calorimetry and use of the fatty acid spin label, 16-S-SL, in order to determine (i) the effect of basic protein on the metastable phase behavior experienced by this lipid, and (ii) to determine if basic protein perturbs the lipid packing as it does with some acidic phospholipids. The effects of basic protein on the thermodynamic parameters of the lipid phase transition were compared with those of polylysine which has an ordering effect on acidic phospholipids as a result of its electrostatic interactions with the lipid head groups. Different synthetic species of cerebroside sulfate of varying fatty acid chain length and with and without a hydroxy fatty acid were used. The non-hydroxy fatty acid forms of cerebroside sulfate undergo a transition from a metastable to a more ordered stable state while the hydroxy fatty acid forms remain in the metastable state at the cation concentration used in this study (0.01 M Na+ or K+). The non-hydroxy fatty acid forms were still able to go into a stable state in the presence of both basic protein and polylysine. At low concentrations, basic protein increased the rate of the transition to the stable state, while polylysine decreased it for the longest chain length form studied. However, at high concentrations, basic protein probably prevented formation of the stable state. The hydroxy fatty acid forms did not go into the stable state in the presence of basic protein and polylysine. It is argued that the increased rate of formation of the stable state in the presence of basic protein and decreased rate in the presence of polylysine are consistent with interdigitation of the lipid acyl chains in the stable state. Basic protein also had a small perturbing effect on the lipid. It decreased the total enthalpy of the lipid phase transition. When added to the non-hydroxy fatty acid forms it increased the temperature of the liquid crystalline to metastable phase transition and decreased the temperature of the stable to liquid crystalline phase transition. It significantly decreased the transition temperature of the hydroxy fatty acid forms but only a portion of the lipid was affected. In contrast, polylysine increased the transition temperature of the metastable and stable states of all forms of cerebroside sulfate but had a greater effect on the non-hydroxy fatty acids forms than on the hydroxy fatty acid forms.(ABSTRACT TRUNCATED AT 400 WORDS)
通过差示扫描量热法以及使用脂肪酸自旋标记物16-S-SL，研究了髓鞘碱性蛋白对髓鞘脂质硫酸脑苷脂的影响，目的是确定：（i）碱性蛋白对该脂质所经历的亚稳相行为的影响；（ii）确定碱性蛋白是否像对某些酸性磷脂那样扰乱脂质堆积。将碱性蛋白对脂质相变热力学参数的影响与聚赖氨酸的影响进行了比较，聚赖氨酸由于与脂质头部基团的静电相互作用而对酸性磷脂具有有序化作用。使用了不同脂肪酸链长度、有或没有羟基脂肪酸的不同合成硫酸脑苷脂种类。硫酸脑苷脂的非羟基脂肪酸形式会从亚稳态转变为更有序的稳定状态，而羟基脂肪酸形式在本研究使用的阳离子浓度（0.01 M Na+或K+）下保持在亚稳态。非羟基脂肪酸形式在碱性蛋白和聚赖氨酸存在下仍能进入稳定状态。在低浓度时，碱性蛋白增加了向稳定状态转变的速率，而聚赖氨酸对所研究的最长链长度形式则降低了该速率。然而，在高浓度时，碱性蛋白可能阻止了稳定状态的形成。羟基脂肪酸形式在碱性蛋白和聚赖氨酸存在下不会进入稳定状态。有人认为，在碱性蛋白存在下稳定状态形成速率增加而在聚赖氨酸存在下速率降低，这与稳定状态下脂质酰基链的叉指化一致。碱性蛋白对脂质也有轻微的扰动作用。它降低了脂质相变的总焓。当添加到非羟基脂肪酸形式中时，它提高了液晶相向亚稳相转变的温度，并降低了稳定相向液晶相转变的温度。它显著降低了羟基脂肪酸形式的转变温度，但仅一部分脂质受到影响。相比之下，聚赖氨酸提高了所有形式硫酸脑苷脂亚稳态和稳定态的转变温度，但对非羟基脂肪酸形式的影响比对羟基脂肪酸形式的影响更大。（摘要截断于400字）
