The transmembrane helices of beef heart cytochrome oxidase.
The transmembrane helices of beef heart cytochrome oxidase.
复制标题
牛心细胞色素氧化酶的跨膜螺旋。
DOI：
10.1016/s0006-3495(87)83395-7
复制
发表时间：
1987
影响因子：
3.4
通讯作者：
Powers,L
中科院分区：
文献类型：
--
作者：
Lundeen,M;Chance,B;Powers,L
用改进的von Heijne-Blomberg疏水性标度预测了牛心细胞色素氧化酶12个亚基中跨膜螺旋的位置。基于每个跨膜螺旋约20个残基，预计估计的660个螺旋残基中约有480个（占1，793个总残基的36.8%）位于跨膜螺旋中，其轴与膜平面的法线倾斜一个小角度α。基于从多层膜的圆二色性（CD）测量获得的39°的观察到的总倾斜角θ，该角度被计算为约30°，或者基于从膜的红外线性二色性获得的36°的观察到的倾斜角θ，该角度被计算为约25°。对于每个跨膜螺旋21个残基，α的计算值分别变为32°和28°，这取决于所使用的θ值。因此，如果20-21个残基足以跨越膜，则跨膜螺旋倾斜角为1.30 °，这说明细胞色素氧化酶中预测的跨膜伸展。脂质头部区域中的额外螺旋残基可偏离细胞色素氧化酶中膜平面的法线较大的角度。
The locations of the transmembrane helices in the 12 subunits of beef heart cytochrome oxidase were predicted with a modified form of the von Heijne-Blomberg hydrophobicity scale. Based on ∼20 residues per transmembrane helix, about 480 of the estimated 660 helical residues (36.8% of 1,793 total residues) are expected to be in transmembrane helices that have their axes tilted by a small angle α from the normal to the plane of the membrane. This angle is calculated to be ∼30°, based on the observed overall tilt angle θ of 39° obtained from circular dichroism (CD) measurements on multilamellar films, or about 25°, based on the observed tilt angle θ of 36° obtained from the infrared linear dichroism of films. For 21 residues per transmembrane helix, the calculated values of α become 32° and 28°, respectively, depending upon the value of θ used. Thus, a transmembrane helical tilt angle of ∼30° accounts for the predicted transmembrane stretches in cytochrome oxidase if 20–21 residues are sufficient to span the membrane. Additional helical residues in the lipid head region may deviate by a larger angle from the normal to the plane of the membrane in cytochrome oxidase.