X-ray diffraction observations of chemically skinned frog skeletal muscle processed by an improved method.
X-ray diffraction observations of chemically skinned frog skeletal muscle processed by an improved method.
复制标题
采用改进方法处理的化学剥皮青蛙骨骼肌的 X 射线衍射观察。
DOI：
10.1016/s0006-3495(80)85074-0
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发表时间：
1980
影响因子：
3.4
通讯作者：
Reedy,MK
中科院分区：
文献类型：
--
作者：
Magid,A;Reedy,MK
整个青蛙缝匠肌可以在大约2小时内用含有0.5% Triton X-100的松弛溶液进行化学剥皮。活体肌肉的x射线衍射图的强度和顺序在这种剥皮后很大程度上保留了下来，表明原纤维和细丝的天然结构保留得很好。使用（mM）： 75k醋酸盐的溶液获得最佳x射线结果；醋酸5毫克；5 ATP;5 EGTA;15k磷酸盐，2% PVP, pH 7.0。赤道x线图显示，洗涤剂皮敷后肌原纤维肿胀，机械皮敷后也观察到。这种肿胀可以通过在提取液中加入高分子量胶体（PVP或葡聚糖）来逆转。通过寻找恢复体内纤维间距所需的胶体渗透压（3% PVP, 4 X 10(4) mol wt），在标准的kcl基松弛溶液中估计膨胀压力为35 Torr。溶胀压力和溶胀程度均小于乙酸取代氯离子为主阴离子。洗洁精皮肤肌肉失去了完整肌肉中肌节长度和晶格间距的等体积关系。在恒定肌节长度下，A带间距的变化与I带和z带间距的变化是平行的。洗洁精剥皮后，i1,0上升，i1,1下降，松弛方向发生变化。由于钙离子浓度从pca9提高到pca6.7对赤道或轴向x射线模式没有影响，我们得出结论，这些强度变化不是由于钙依赖的过桥运动，而是由于A带细丝的无序化。
Whole frog sartorius muscles can be chemically skinned in approximately 2 h by relaxing solutions containing 0.5% Triton X-100. The intensity and order of the X-ray diffraction pattern from living muscle is largely retained after such skinning, indicating good retention of native structure in fibrils and filaments. Best X-ray results were obtained using a solution with (mM): 75 K acetate; 5 Mg acetate; 5 ATP; 5 EGTA; 15 K phosphate, 2% PVP, pH 7.0. Equatorial X-ray patterns showed that myofibrils swell after detergent skinning, as also observed after mechanical skinning. This swelling could be reversed by adding high molecular weight colloids (PVP or dextran) to the extracting solution. By finding the colloid osmotic pressure needed to restore the in vivo interfilament spacing (3% PVP, 4 X 10(4) mol wt) the swelling pressure was estimated as 35 Torr in a standard KCl-based relaxing solution. The swelling pressure and the extent of swelling were less than acetate replaced chloride as the major anion. Detergent-skinned muscle lost the constant-volume relation between sarcomere length and lattice spacing seen in intact muscle. Changes in A band spacing were paralleled by changes in I and band-Z line spacing at a constant sarcomere length. After detergent skinning, I1,0 rose while I1,1 fell, a change in the relaxing direction. Since raising the calcium ion concentrations from pCa 9 to PCa 6.7 was without effect on equatorial or axial X-ray patterns, we concluded that these intensity changes were not due to calcium-dependent cross-bridge movement but rather to disordering of thin filaments in the A band.