Biomedical science最新文献_第3页

Mechanism of aggregation of fibrinogen molecules: the influence of fibrin-stabilising factor. 纤维蛋白原分子聚集的机制:纤维蛋白稳定因子的影响。

Biomedical science Pub Date : 1991-01-01

M A Rozenfel'd, M V Vasil'eva

{"title":"Mechanism of aggregation of fibrinogen molecules: the influence of fibrin-stabilising factor.","authors":"M A Rozenfel'd, M V Vasil'eva","doi":"","DOIUrl":"","url":null,"abstract":"The physicochemical mechanism of aggregation of fibrinogen has been investigated in the presence and absence of fibrin-stabilising factor (factor XIIIa). Data from elastic and inelastic light-scattering and viscometry show that molecules of fibrinogen undergo a spontaneous modification of their carboxyl terminals and bind 'end to end' into flexible polymer chains. On attaining a critical length, the single-filament polymers twist into a coil and aggregate to form branched molecules in which the segments are packed sufficiently densely to resemble strongly hydrated globular particles. The formation, under the influence of factor XIIIa, of epsilon/gamma-glutamyl-lysine covalent bonds produces only insignificant changes in the spatial organisation of the fibrinogen aggregates. Covalent dimerisation of the gamma-chains restricts the structural flexibility of the polymers, but linking of the alpha-chains provides progressive compaction of the structure with increase in molecular weight. Electrophoresis of reconstituted samples shows that the coil-shaped chains of fibrinogen oligomers prevent the complete enzymatic linking of the gamma-chains. The results of this work suggest that the accelerated assembly of multimolecular aggregates, seen in the presence of factor XIIIa, may be explained by the stabilisation of intermediate complexes of fibrinogen, which makes the spontaneous transition from a stable native state to the activated state irreversible.","PeriodicalId":77499,"journal":{"name":"Biomedical science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1991-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12850310","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

In vitro activation of protein kinase C by prolactin in guinea pig adrenal cortex. 催乳素对豚鼠肾上腺皮质蛋白激酶C的体外活化作用。

Biomedical science Pub Date : 1991-01-01

Sautin YuYu, N D Tron'ko, A S Mikosha

引用次数: 0

Mössbauer spectroscopy of oxygenated haemoglobins. Mössbauer氧合血红蛋白光谱。

Biomedical science Pub Date : 1991-01-01

V E Prusakov, R A Stukan, V I Gol'danskii

{"title":"Mössbauer spectroscopy of oxygenated haemoglobins.","authors":"V E Prusakov, R A Stukan, V I Gol'danskii","doi":"","DOIUrl":"","url":null,"abstract":"Murine tetrameric oxyhaemoglobin and insect monomeric erythrocruorin were studied. A doublet with the Lorentz form of lines (delta EQ = 2.22 mm s-1; delta alpha-Fe = 0.27 mm s-1; gamma 1/2 = 0.29 mm s-1) was observed in the oxyhaemoglobin spectrum at 4.2 K. In the 80-170 K interval the doublet components are distorted, but at T greater than 175 K, the lines again become symmetrical. In the 175-210 K region the value of gamma 1/2 is approximately 0.42 mm s-1. The profiles of the oxyhaemoglobin spectra are not dependent on the nature of the samples (blood; whole, or in aqueous or water-glycerol solutions at different pH values), or on the rate at which the latter are frozen. The oxyerythrocruorin spectra in aqueous solution and in a water-glycerol solution at 80 K and 170 K were doublets with Lorentz lines (the delta EQ values are equal to 2.20 mm s-1 and 2.12 mm s-1, respectively). It is concluded that the characteristics of the oxyhaemoglobin spectra reflect the specific electronic and structural properties of the oxy-complex in this protein. It was found that the oxyhaemoglobin spectra are very adequately described by two doublets with equal delta and gamma 1/2 values, but with different delta EQ values and relative intensities. A model is described in which these doublets correspond to two types of hydrogen bond associated with the distal histidine (E7), involving the terminal atom of molecular oxygen and the oxygen atom bound with the haem iron, respectively.","PeriodicalId":77499,"journal":{"name":"Biomedical science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1991-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12935360","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

Presynaptic alpha-latrotoxin receptor components interact with protein p65 of synaptic vesicle membranes. 突触前α -干酪毒素受体组分与突触囊泡膜蛋白p65相互作用。

Biomedical science Pub Date : 1991-01-01

I N Surkova, E V Grishin

引用次数: 0

A mathematical model for the interaction between cytotoxic T lymphocytes and tumour cells. Analysis of the growth, stabilization, and regression of a B-cell lymphoma in mice chimeric with respect to the major histocompatibility complex. 细胞毒性T淋巴细胞与肿瘤细胞相互作用的数学模型。与主要组织相容性复合物相关的小鼠嵌合b细胞淋巴瘤的生长、稳定和消退分析。

Biomedical science Pub Date : 1991-01-01

V A Kuznetsov

引用次数: 0

The effect of tryptophan on the phenobarbital-mediated induction of cytochrome P-450 in rat liver. The role of tryptophan 2,3-dioxygenase. 色氨酸对苯巴比妥介导的大鼠肝脏细胞色素P-450的影响。色氨酸2,3-双加氧酶的作用。

Biomedical science Pub Date : 1991-01-01

P A Kaliman, S P Manandhar

{"title":"The effect of tryptophan on the phenobarbital-mediated induction of cytochrome P-450 in rat liver. The role of tryptophan 2,3-dioxygenase.","authors":"P A Kaliman, S P Manandhar","doi":"","DOIUrl":"","url":null,"abstract":"The effect of intraperitoneal administration of phenobarbital (80 mg kg-1 body weight) and tryptophan (200 mg kg-1 body weight), separately or in combination, on the microsomal content of cytochrome P-450 and the activity of tryptophan 2,3-dioxygenase (EC 1.13.11.11) in Wistar rat liver was determined at different time intervals after injection. There was an increase in the amount of cytochrome P-450 within 12 h of administration of a single dose of phenobarbital which was maintained over the next 12 h. Tryptophan had no effect on the amount of cytochrome P-450, but administration of tryptophan in combination with phenobarbital blocked the increase that was found after administration of phenobarbital alone. Both phenobarbital and tryptophan increased tryptophan 2,3-dioxygenase activity (total enzyme and holoenzyme) but had different effects on the rate of activation and the degree of saturation of the enzyme with haem. Administration of tryptophan and phenobarbital in combination invoked the same effect as tryptophan alone. Significant activation of the holoenzyme was found, when tryptophan was administered 2 h after phenobarbital administration. It is proposed that combined administration of phenobarbital and tryptophan leads to substrate stabilisation of tryptophan 2,3-dioxygenase, and that this is accompanied by the binding of the newly synthesised haem, thus making haem unavailable for formation of cytochrome P-450.","PeriodicalId":77499,"journal":{"name":"Biomedical science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1991-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12914711","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

Block copolymers of ethylene oxide and propylene oxide (pluronics) as immunomodulators and antitumour agents. 环氧乙烷和环氧丙烷嵌段共聚物(pluronics)作为免疫调节剂和抗肿瘤剂。

Biomedical science Pub Date : 1991-01-01

I N Topchieva, V N Erokhin, S V Osipova, M M Khrutskaya, T A Kupriyanova, S N Bykovskaya

引用次数: 0

A comparative analysis of the putative regulatory regions in human genes for the alpha-subunit family of Na(+)-K+ ATPase. Na(+)-K+ atp酶α亚基家族在人类基因中可能调控区域的比较分析。

Biomedical science Pub Date : 1991-01-01

I V Malyshev, D A Bessarab, Orlova MYu, K E Petrukhin, S V Volik, N E Broude, G S Monastyrskaya, N N Modyanov, E D Sverdlov

{"title":"A comparative analysis of the putative regulatory regions in human genes for the alpha-subunit family of Na(+)-K+ ATPase.","authors":"I V Malyshev, D A Bessarab, Orlova MYu, K E Petrukhin, S V Volik, N E Broude, G S Monastyrskaya, N N Modyanov, E D Sverdlov","doi":"","DOIUrl":"","url":null,"abstract":"The sequences of a 1.5 kb long stretch of the 5' flanking region of the gene for the alpha 3 isoform of the catalytic subunit of human Na(+)-K+ ATPase (located on chromosome 19) and of more than a 2 kb stretch of the 5' flanking region of the gene for the alpha 2 isoform (located on chromosome 1) have been determined. Transcription start sites for the gene for the alpha 3 isoform have been mapped at positions -152 and -155 relative to the translation initiation codon by primer extension analysis and S1-nuclease mapping of mRNA from human brain. The 5' flanking region of the gene for isoform alpha 3 contains a CCAAT box on the noncoding chain and six putative Sp1 binding sites. Absence of a conventional TATA box and a high GC content are other features of the region. The 5' upstream region of the gene for the alpha 2 isoform contains potential TATA and CCAAT boxes and one potential Sp1 binding site. Upstream of the putative TATA box there is an octanucleotide repeat, GGGGGAGA, which is also found in several eukaryotic genes in analogous positions. Pairwise comparison of the putative 5' regulatory regions of the genes coding for the different isoforms of the Na(+)-K(+)-ATPase catalytic subunit shows the existence of conserved elements, as well as of oligonucleotide blocks with very different structures. It is suggested that the differences in the primary structure of the 5' upstream regions may provide the basis for tissue-specific expression of the Na(+)-K(+)-ATPase isoforms.","PeriodicalId":77499,"journal":{"name":"Biomedical science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1991-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12820990","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

Proper cotranslational insertion of visual rhodopsin into the lipid bilayer occurs in the absence of protein translocation machinery. 视紫红质适当的共翻译插入到脂质双分子层发生在缺乏蛋白质转运机制。

Biomedical science Pub Date : 1991-01-01

V V Gurevich, I D Pokrovskaya, M N Garnovskaya, I L Dumler, S A Zozulya

引用次数: 0

Affinity-purified secretory immunoglobulin A possesses the ability to phosphorylate human milk casein. 亲和纯化的分泌性免疫球蛋白A具有磷酸化人乳酪蛋白的能力。

Biomedical science Pub Date : 1991-01-01

Y Y Kit, A A Kim, V N Sidorov

引用次数: 0