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首页> 外文期刊>Biochemistry >ADP binding induces long-distance structural changes in the beta polypeptide of the chloroplast ATP synthase.
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ADP binding induces long-distance structural changes in the beta polypeptide of the chloroplast ATP synthase.

机译:ADP结合可诱导叶绿体ATP合酶的β多肽发生长距离结构变化。

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摘要

Binding of ADP to the beta polypeptide isolated from the catalytic F1 portion (CF1) of the chloroplast ATP synthase caused an increase of 10-20% in the steady state fluorescence intensity of fluorescent maleimides attached to the cysteine residue at position 63. Fluorescence lifetime distributions indicated that the beta polypeptide switched between two conformational states depending on the presence or absence of bound ADP. The fluorescence enhancement induced by ADP binding allowed a direct calculation of the dissociation constant for ADP of 0.7 microM. ATP did not cause a fluorescence enhancement but competed with ADP for binding to the same site. An apparent dissociation constant of 2 microM was obtained for ATP binding. Fluorescence resonance energy transfer experiments indicated that Cys63 is 42 A away from the nucleotide binding site on the beta polypeptide, confirming a previous measurement [(Colvert, K.K., Mills, D.A., Richter, M.L. (1992) Biochemistry 31, 3930-3935]. Frequency domain fluorescence anisotropy measurements indicated that the beta polypeptide has an irregular, elongated shape which is in good agreement with the conformation found in the crystal structure of the beef heart mitochondrial F1 enzyme [Abrahams, J.P., Leslie, A.G.W., Lutter, R., & Walker, J.E. (1994) Nature 370, 621-628]. The rotational correlation time did not change significantly upon ADP binding, indicating that ADP did not induce a large change in the overall shape of the beta polypeptide. The results show that the nucleotide binding domain and the N-terminal domain of the beta polypeptide communicate with each other over a significant distance via conformational changes.(ABSTRACT TRUNCATED AT 250 WORDS)
机译:ADP与从叶绿体ATP合酶的催化性F1部分(CF1)分离的β多肽的结合,导致在位置63处的半胱氨酸残基上附着的荧光马来酰亚胺的稳态荧光强度增加10-20%。荧光寿命分布指出β多肽根据结合的ADP的存在或不存在在两种构象状态之间切换。由ADP结合诱导的荧光增强使得可以直接计算0.7 microM的ADP的解离常数。 ATP不会引起荧光增强,但会与ADP竞争与相同位点的结合。对于ATP结合,获得了2 microM的表观解离常数。荧光共振能量转移实验表明Cys63与β多肽上的核苷酸结合位点相距42 A,证实了先前的测量[(Colvert,KK,Mills,DA,Richter,ML(1992)Biochemistry 31,3930-3935)。频域荧光各向异性测量表明,β多肽具有不规则的细长形状,与牛肉心线粒体F1酶[Abrahams,JP,Leslie,AGW,Lutter,R., &Walker,JE(1994)Nature 370,621-628]。旋转相关时间在ADP结合后并没有显着变化,表明ADP不会引起β多肽整体形状的大变化。 β多肽的核苷酸结合结构域和N末端结构域通过构象变化在相当长的距离上相互连通。(摘要截短为250字)

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