The light-harvesting polypeptides of Rhodopseudomonas sphaeroides R-26.1. I. Isolation, purification and sequence analyses.-猫眼课题宝

球形红假单胞菌 R-26.1 的光捕获多肽。

DOI：

10.1515/bchm2.1984.365.2.703

发表时间：

1984

期刊：

Hoppe-Seyler's Zeitschrift fur physiologische Chemie

影响因子：

通讯作者：

中科院分区：

文献类型：

作者：

R. Theiler;F. Suter;V. Wiemken;H. Zuber

采用凝胶过滤和有机溶剂离子交换层析相结合的方法，从红球藻蓝绿突变体R-26.1的色素细胞膜中分离纯化了4种小分子量多肽。在十二烷基硫酸盐聚丙烯酰胺凝胶上，纯化的多肽与已知与触角色素蛋白复合物相关的LH-1、LH-2和LH-3带共迁移。完整的一级结构，阐明了通过自动埃德曼降解的完整的多肽和重叠的C-末端片段化学裂解后获得的色氨酸和甲硫氨酸残基。通过肼解验证C-末端，在无法获得重叠C-末端片段的情况下，通过羧肽酶A消化验证。这四种多肽显示出三重结构：即极性N-末端区域与极性C-末端区域被约21个主要疏水氨基酸残基的区段分开。所有疏水片段均含有特征性保守组氨酸残基。C-末端区域在两个多肽中被还原为仅几个氨基酸，这两个多肽一起形成LH-3带，即LH-3A和LH-3B。其延伸的N-末端区域富含带电残基，并在靠近疏水段开始处含有额外的保守组氨酸残基。这些特性将LH-3 A和LH-3 B归入亚组（β多肽：分别为B 870-β和B 850-β）。LH-1和LH-2似乎形成了另一个亚组（α-多肽：分别为B 870-α和B 850-α），这是在其序列中搜索保守元件（分类的结构基础）时提出的。用完整的触角色素蛋白复合物进行的N-末端分析揭示了以下内容：（i）LH-1和LH-3与Rp中的B 870复合物相关。sphaeroides 24.1（野生型），（ii）相同的多肽几乎只存在于色素细胞膜的RP。sphaeroides R-26，一种蓝绿色突变体，在870 nm处吸收，（iii）LH-2和LH-3 B是Rp的B 800-850复合物的组成多肽。sphaeroides 2.4.1和分离自蓝-绿突变体R-26.1的光谱改变的B 850复合物，其在860 nm处吸收。该突变体含有LH-2和LH-3B沿着LH-1和LH-3A，并且显然能够形成两种类型的触角复合体。（400字处截断摘要）

Four low-molecular-mass polypeptides were isolated and purified from chromatophore membranes of Rhodopseudomonas sphaeroides blue-green mutant R-26.1 by a combination of gel filtration and ion-exchange chromatography in organic solvents. On dodecyl sulfate polyacrylamide gels, the purified polypeptides comigrate with bands LH-1, LH-2 and LH-3 known to be related to the antenna-pigment-protein complexes. The complete primary structures were elucidated by automated Edman degradation of the intact polypeptides and of overlapping C-terminal fragments obtained after chemical cleavage at tryptophan and methionine residues. The C-termini were verified by hydrazinolysis and, in one case where an overlapping C-terminal fragment could not be obtained, by digestion with carboxypeptidase A. The four polypeptides show a tripartite structure: i.e. a polar N-terminal region is separated from a polar C-terminal region by a segment of about 21 predominantly hydrophobic amino-acid residues. All hydrophobic segments contain a characteristic conservative histidine residue. The C-terminal region is reduced to only a few amino acids in the two polypeptides which together form band LH-3, i.e. LH-3A and LH-3B. Their extended N-terminal region is rich in charged residues and contains an additional conserved histidine residue close to the beginning of the hydrophobic segment. These properties place LH-3A and LH-3B into subgroup (beta-polypeptides: B 870-beta and B 850-beta, respectively). LH-1 and LH-2 appear to form another subgroup (alpha-polypeptides: B 870-alpha and B 850-alpha, respectively) as suggested during a search for conservative elements within their sequences (structural basis for classification). N-Terminal analyses carried out with intact antenna-pigment-protein complexes revealed the following: (i) LH-1 and LH-3 are associated with the B 870 complex in Rp. sphaeroides 24.1 (wild type), (ii) the same polypeptides are almost exclusively present in chromatophore membranes of Rp. sphaeroides R-26, a blue-green mutant which absorbs at 870 nm, (iii) LH-2 and LH-3B are the constituent polypeptides of the B 800-850 complex of Rp. sphaeroides 2.4.1 and of the spectrally altered B 850 complex isolated from the blue-green mutant R-26.1 which absorbs at 860 nm. This mutant contains LH-2 and LH-3B along with LH-1 and LH-3A and apparently is able to form both types of antenna complexes.(ABSTRACT TRUNCATED AT 400 WORDS)

Conformational studies of the synthetic precursor-specific region of preproparathyroid hormone.