Biofizika最新文献_第7页

[Some Features of Sound Signal Envelope by the Frog's Cochlear Nucleus Neurons]. [青蛙耳蜗核神经元声信号包络的一些特征]。

Biofizika Pub Date : 2015-05-01

N G Bibikov

{"title":"[Some Features of Sound Signal Envelope by the Frog's Cochlear Nucleus Neurons].","authors":"N G Bibikov","doi":"","DOIUrl":"","url":null,"abstract":"The responses of single neurons in the medullar auditory center of the grass frog were recorded extracellularly under the action of long tonal signals of the characteristic frequency modulated by repeating fragments of low-frequency (0-15 Hz, 0-50 Hz or 0-150 Hz) noise. Correlation method was used for evaluating the efficacy of different envelope fragments to ensure generation of a neuron pulse discharge. Carrying out these evaluations at different time intervals between a signal and a response the maximum delays were assessed. Two important envelope fragments were revealed. In majority of units the most effective was the time interval of the amplitude rise from mean value to maximum, and the fragment where the amplitude fall from maximum to mean value was the second by the efficacy. This type of response was observed in the vast majority of cells in the range of the envelope frequency bands 0-150 and 0-50 Hz. These cells performed half-wave rectification of such type of the envelope. However, in some neurons we observed more strong preference toward a time interval with growing amplitude, including even those where the amplitude value was smaller than the mean one. These properties were observed mainly for low-frequency (0-15 Hz) modulated signals at high modulation depth. The data show that even in medulla oblongata specialization of neural elements of the auditory pathway occurs with respect to time interval features of sound stimulus. This diversity is most evident for signals with a relatively slowly varying amplitude.","PeriodicalId":8942,"journal":{"name":"Biofizika","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34053618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

[Effects of Medium Viscosity Increasing Agents on ATP Synthesis in Chloroplast Thylakoids]. [介质增粘剂对叶绿体中 ATP 合成的影响］

Biofizika Pub Date : 2015-05-01

I M Kartashov, V K Opanasenko, A N Malyan

{"title":"[Effects of Medium Viscosity Increasing Agents on ATP Synthesis in Chloroplast Thylakoids].","authors":"I M Kartashov, V K Opanasenko, A N Malyan","doi":"","DOIUrl":"","url":null,"abstract":"The effect of an increase in the medium viscosity on cyclic photophosphorylation in chloroplast thylakoids and on Ca2+ -dependent ATP hydrolysis by the chloroplast coupling factor CF, was studied. With 0.1-0.2 mM ADP used it was found that the rate of ATP synthesis decreases after addition of various agents that increase the medium viscosity (sucrose, dextran 40 or polyethylene glycol 6000 provided that these agents cause neither uncoupling nor electron transport inhibition in the absence of ADP. Dextran and polyethylene glycol inhibited ATP synthesis by 50% when their concentrations were much lower (6-10%) than that of sucrose (30-40%), while 50% inhibition of Ca2+ -dependent ATP hydrolysis by CFI-ATPase was observed at higher concentrations of dextran and polyethylene glycol (9-13%) and lower concentrations of sucrose (about 20%). For ADP, the effective Michaelis constant (KM) was shown to increase 2-3-fold with the increasing viscosity; meanwhile the maximal rate of cyclic photophosphorylation remained virtually unchanged. The dependence of K(M) on the medium viscosity can serve as a criterion for the process of diffusion-controlled photophosphorylation. Possible mechanisms of ADP and ATP diffusion are discussed.","PeriodicalId":8942,"journal":{"name":"Biofizika","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34053615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

[Comparison of Physico-chemical Aspects between E. coli and Human Dihydrofolate Reductase: an Equilibrium Unfolding Study]. [大肠杆菌与人二氢叶酸还原酶理化方面的比较:一项平衡展开研究]。

Biofizika Pub Date : 2015-05-01

Charu Thapliyal, Neha Jain, Pratima Chaudhuri

{"title":"[Comparison of Physico-chemical Aspects between E. coli and Human Dihydrofolate Reductase: an Equilibrium Unfolding Study].","authors":"Charu Thapliyal, Neha Jain, Pratima Chaudhuri","doi":"","DOIUrl":"","url":null,"abstract":"A protein, differing in origin, may exhibit variable physicochemical behaviour, difference in sequence homology, fold and function. Thus studying structure-function relationship of proteins from altered sources is meaningful in the sense that it may give rise to comparative aspects of their sequence-structure-function relationship. Dihydrofolate reductase is an enzyme involved in cell cycle regulation. It is a significant enzyme as.a target for developing anticancer drugs. Hence, detailed understanding of structure-function relationships of wide variants of the enzyme dihydrofolate reductase would be important for developing an inhibitor or an antagonist against the enzyme involved in the cellular developmental processes. In this communication, we have reported the comparative structure-function relationship between E. coli and human dihydrofolate reductase. The differences in the unfolding behaviour of these two proteins have been investigated to understand various properties of these two proteins like relative' stability differences and variation in conformational changes under identical denaturing conditions. The equilibrium unfolding mechanism of dihydrofolate reductase proteins using guanidine hydrochloride as a denaturant in the presence of various types of osmolytes has been monitored using loss in enzymatic activity, intrinsic tryptophan fluorescence and an extrinsic fluorophore 8-anilino-1-naphthalene-sulfonic acid as probes. It has been observed that osmolytes, such as 1M sucrose, and 30% glycerol, provided enhanced stability to both variants of dihydrofolate reductase. Their level of stabilisation has been observed to be dependent on intrinsic protein stability. It was observed that 100 mM proline does not show any 'significant stabilisation to either of dihydrofolate reductases. In the present study, it has been observed that the human protein is relatively less stable than the E.coli counterpart.","PeriodicalId":8942,"journal":{"name":"Biofizika","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34053614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

[Molecular Dynamics Simulations of Self-organization of the Structure of Model Biomimetic Polymers]. [模型仿生聚合物结构自组织的分子动力学模拟]。

Biofizika Pub Date : 2015-05-01

K V Shaitan, I V Fedik

引用次数: 0

[Structural and Physicochemical Characteristics of Conformationally Stable alpha-Helical Oligopeptides]. [构象稳定的α -螺旋寡肽的结构和物理化学特征]。

Biofizika Pub Date : 2015-05-01

A V Batyanovskii, I D Volotovsky, V A Namiot, I V Filatov, I A Galkin, N V Gnuchev, G Tumanyan, N G Esipova

{"title":"[Structural and Physicochemical Characteristics of Conformationally Stable alpha-Helical Oligopeptides].","authors":"A V Batyanovskii, I D Volotovsky, V A Namiot, I V Filatov, I A Galkin, N V Gnuchev, G Tumanyan, N G Esipova","doi":"","DOIUrl":"","url":null,"abstract":"The analysis of conformationally stable (conformational conservative) tetrapeptides selected from protein structures deposited in PDBSelect data bank has been fulfilled. The subset contained 943 tetrapeptide amino acid sequences and there were merely five 3D protein segment representatives for each sequence. As a result, the conclusion has been drawn on the basis of DSSP annotation analysis that in the majority of cases (900 of 943) alpha-helical conformation is obvious. Different than alpha-helix, in particular, the left-handed polyproline II helical conformation was observed in 43 sequences. The physical and chemical properties of conformationally stable peptides taken from the appropriate sample were estimated by the average hydrophobicity/hydrophilicity of tetrapeptides. The results of calculations show that the \"neutrality\" towards hydrophobicity/hydrophilicity is representative of conformationally stable oligopeptides. It should be noted, that dispersion of hydrophobicity/hydrophilicity distribution is sufficiently lower than for the test subsets. Thus, the conformationally stable oligopeptides present a distinct group of local protein structures which are very close with respect to conformational and physicochemical properties. In accordance with our developed theory of specific long range interactions these peptides are the objects being quite useful for effective mutual molecular recognition.","PeriodicalId":8942,"journal":{"name":"Biofizika","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33987073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

[Investigation of Free Radical Processes in Substrates and Biological Samples by Means of induced Chemiluminescence]. 用诱导化学发光的方法研究底物和生物样品中的自由基过程。

Biofizika Pub Date : 2015-05-01

I M Piskarev, S V Trofimova, O E Burkhina, I P Ivanova

引用次数: 0

[Action of Combined Magnetic Fields with a Very Weak Low-frequency Alternating Component on Luminol-dependent Chemiluminescence in Mammalian Blood]. [联合磁场与极弱低频交变分量对哺乳动物血液中鲁米诺依赖性化学发光的作用]。

Biofizika Pub Date : 2015-05-01

V V Novikov, E N Yablokova, E E Fesenko

引用次数: 0

[Approximation of Time Series of Paramecia caudatum Dynamics by Verhulst and Gompertz Models: Non-traditional Approach]. [用Verhulst和Gompertz模型逼近尾草履虫动力学的时间序列:非传统方法]。

Biofizika Pub Date : 2015-05-01

L V Nedorezov

引用次数: 0

[Signs of the Impact of the Earth's core on the Planet's Population]. [地核对地球人口影响的迹象]。

Biofizika Pub Date : 2015-05-01

Yu P Malyshkov, S Yu Malyshkov

引用次数: 0

[Particularities of Spatial Organization of Human Hemokinin-1 and Mouse/Rat Hemokinin-1 Molecules]. 人血红素-1与小鼠/大鼠血红素-1分子空间组织的特殊性

Biofizika Pub Date : 2015-05-01

G A Agaeva, U T Agaeva, N M Godjaev

{"title":"[Particularities of Spatial Organization of Human Hemokinin-1 and Mouse/Rat Hemokinin-1 Molecules].","authors":"G A Agaeva, U T Agaeva, N M Godjaev","doi":"","DOIUrl":"","url":null,"abstract":"By molecular mechanics method the conformational properties of two molecules of the tachykinin family, human hemokinin-1 and mouse/rat hemokinin-1, each consisting of 11 amino acids, have been investigated. On the basis of a step-by-step approach we determined the energetically favorable spatial structures of these molecules and their fragments represented as a set of conformations characterized by the relatively labile N-terminal tripeptide and conformationally rigid C-terminal segment. It was shown that conformationally conservative C-terminal octapeptide of the molecules preferably forms two conformations with different structural types of the peptide chain. One of these conformations has an alpha-helical structure, and the other forms the chain's turn that led to an alpha helical turn at the C-terminus. As a result of calculations the energetically favorable ranges of the values of the dihedral angles and orientations of all the residues in low energy conformational states of the molecules were shown. Due to conformational analysis of separate fragments it was possible to trace the process of the second structure formation in these molecules. Based on the results obtained the contribution of inter-residues interaction energy was determined and the role of the each residue in the formation of the optimal spatial structures of hemokinin-1 molecules was estimated.","PeriodicalId":8942,"journal":{"name":"Biofizika","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34053613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0