Biofizika最新文献

英文中文

[Effect of water soluble non-membrane proteins on the phospholipid structure]. [水溶性非膜蛋白对磷脂结构的影响]。

Biofizika

Pub Date : 2002-03-01

G M Sorokoumova, A A Selishcheva, O P Tiurina, S G Alekseeva, O M Martynova, T V Sharf, V I Shvets

The interaction of water-soluble nonmembraneous proteins (trypsin and the basic pancreatic trypsin inhibitor (BPTI)) with soybean phospholipids was studied using multilamellar vesicles. Multilamellar vesicles were obtained from soybean lipid extracts and mixtures of individual phospholipids based on phosphatidylcholine. These mixtures contain different phospholipids: "bilayer", "nonbilayer", and negatively charged. It was shown that the content of both proteins in the complex depends on pH and the presence of negatively charged components. On the basis of this finding, the conclusion about the electrostatic nature of lipid-protein interaction was made. The structural organization of soybean phospholipids in multilamellar vesicles was studied in the presence and absence of the proteins using broad-line 31P-NMR spectroscopy. It was found that, in mixtures of phospholipids of complex composition, different types of phases coexist, and phospholipids of different classes can compensate the effects of each other. Trypsin and BPTI affect the structure of phospholipids in a similar way, inducing considerable structural changes in multilamellar vesicles of preparations containing negatively charged components in whose structure there coexisted primordially the bilayer and isotropic phases.

我们利用多胶束囊泡研究了水溶性非膜蛋白质（胰蛋白酶和碱性胰蛋白酶抑制剂（BPTI））与大豆磷脂的相互作用。多胶束囊泡是从大豆脂质提取物和以磷脂酰胆碱为基础的单个磷脂混合物中获得的。这些混合物含有不同的磷脂："双层"、"非双层 "和带负电荷。研究表明，复合物中两种蛋白质的含量取决于 pH 值和带负电荷成分的存在。根据这一发现，得出了脂质与蛋白质相互作用的静电性质的结论。使用宽线 31P-NMR 光谱法研究了多胶束囊泡中大豆磷脂在蛋白质存在和不存在时的结构组织。研究发现，在成分复杂的磷脂混合物中，不同类型的相共存，不同类别的磷脂可以相互补偿。胰蛋白酶和 BPTI 也以类似的方式影响磷脂的结构，在含有带负电成分的多胶束囊泡中引起相当大的结构变化。

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引用次数: 0

[Effect of high magnesium ion concentration on the electron transport rate and proton exchange in thylakoid membranes in higher plants]. [高浓度镁离子对高等植物类囊体膜电子传递速率和质子交换的影响]。

Biofizika

Pub Date : 2001-11-01

A R Ignat'ev, S A Khorobrykh, B N Ivanov

The effects of magnesium ion concentration on the rate of electron transport in isolated pea thylakoids were investigated in the pH range from 4.0 up to 8.0. In the absence of magnesium ions in the medium and in the presence of 5 mM MgCl2 in the experiments not only without added artificial acceptors but also with ferricyanide or methylviologen as an acceptor, this rate had a well-expressed maximum at pH 5.0. It was shown that, after depression to minimal values at pH 5.5-6.5, it gradually rose with increasing pH. An increase in magnesium ion concentration up to 20 mM essentially affected the electron transfer rate: it decreased somewhat at pH 4.0-5.0 but increased at higher pH values. At this magnesium ion concentration, the maximum rate was at pH 6.0-6.5 and the minimum, at pH 7.0. Subsequent rise upon increasing pH to 8.0 was expressed more sharply. The influence of high magnesium ion concentration on the rate of electron transport was not observed in the presence of gramicidin D. It was found that without uncoupler, the changes in the electron transfer rate under the influence of magnesium ions correlated to the changes in the first-order rate constant of the proton efflux from thylakoids. It is supposed that the change in the ability of thylakoids to keep protons by the action of magnesium ions is the result of electrostatic interactions of these ions with the charges on the external surface of membranes. A possible role of regulation of the electron transport rate by magnesium ions in vivo is discussed.

在 pH 值为 4.0 至 8.0 的范围内，研究了镁离子浓度对离体豌豆硫球电子传递速率的影响。在培养基中没有镁离子的情况下，以及在有 5 mM MgCl2 的情况下，实验中不仅没有添加人工受体，而且还添加了铁氰化钾或甲基维罗庚作为受体。实验表明，在 pH 值为 5.5-6.5 时，该速率降至最低值，之后随着 pH 值的增加而逐渐上升。镁离子浓度增加到 20 毫摩尔对电子转移率有本质影响：在 pH 值为 4.0-5.0 时，电子转移率有所下降，但在 pH 值较高时，电子转移率有所上升。在这种镁离子浓度下，pH 值为 6.0-6.5 时电子转移率最大，pH 值为 7.0 时电子转移率最小。当 pH 值升至 8.0 时，上升幅度更大。研究发现，在不使用解偶联剂的情况下，镁离子影响下电子传输速率的变化与质子从硫液泡流出的一阶速率常数的变化相关。据推测，在镁离子的作用下，硫球保持质子的能力发生了变化，这是这些离子与膜外表面的电荷发生静电相互作用的结果。讨论了镁离子在体内调节电子传输速率的可能作用。

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引用次数: 0

[The non-contact effect of substances containing benzene rings and heterocycles on biological systems]. [含有苯环和杂环的物质对生物系统的非接触影响]。

Biofizika

Pub Date : 2001-09-01

Iu P Frolov

It was found that some substances containing benzolic rings and heterocyclic structures have a noncontact effect on biosystems. Some results of experiments dealing with the noncontact effect on enzyme molecules, cells, and uni- and multicellular organisms are presented. Factors influencing the efficiency of the noncontact effect were revealed.

研究发现，一些含有苯环和杂环结构的物质对生物系统具有非接触效应。本文介绍了有关酶分子、细胞、单细胞和多细胞生物体非接触效应的一些实验结果。揭示了影响非接触效应效率的因素。

引用次数: 0

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