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1.
A family of plasmid expression vectors, containing fragments of the E. coli alkaline phosphatase gene (phoA), has been constructed for the lambda PR promoter-directed thermoinducible superproduction of fusions of heterologous polypeptides to the N- or C-terminus of E. coli alkaline phosphatase and its leader peptide. Effective expression and export to periplasm of resulting fusion proteins, which may retain enzymatic activity of the phosphatase, has been shown. 相似文献
2.
3.
For several species of lepidoptera, most of the approximately 350-bp
mitochondrial control-region sequences were determined. Six of these
species are in one genus, Jalmenus; are closely related; and are believed
to have undergone recent rapid speciation. Recent speciation was supported
by the observation of low interspecific sequence divergence. Thus, no
useful phylogeny could be constructed for the genus. Despite a surprising
conservation of control-region length, there was little conservation of
primary sequences either among the three lepidopteran genera or between
lepidoptera and Drosophila. Analysis of secondary structure indicated only
one possible feature in common--inferred stem loops with higher-than-random
folding energies-- although the positions of the structures in different
species were unrelated to regions of primary sequence similarity. We
suggest that the conserved, short length of control regions is related to
the observed lack of heteroplasmy in lepidopteran mitochondrial genomes. In
addition, determination of flanking sequences for one Jalmenus species
indicated (i) only weak support for the available model of insect 12S rRNA
structure and (ii) that tRNA translocation is a frequent event in the
evolution of insect mitochondrial genomes.
相似文献
4.
MF Perutz 《Current opinion in structural biology》1996,6(6):848-858
Several dominantly inherited, late onset, neurodegenerative diseases are due to expansion of CAG repeats, leading to expansion of glutamine repeats in the affected proteins. These proteins are of very different sizes and, with one exception, show no sequence homology to known proteins or to each other; their functions are unknown. In some, the glutamine repeat starts near the N-terminus, in another near the middle and in another near the C-terminus, but regardless of these differences, no disease has been observed in individuals with fewer than 37 repeats, and absence of disease has never been found in those with more than 41 repeats. Protein constructs with more than 41 repeats are toxic to E. coli and to CHO cells in culture, and they elicit ataxia in transgenic mice. These observations argue in favour of a distinct change of structure associated with elongation beyond 37–41 glutamine repeats. The review describes experiments designed to find out what these structures might be and how they could influence the properties of the proteins of which they form part. Poly-
-glutamines form pleated sheets of β-strands held together by hydrogen bonds between their amides. Incorporation of glutamine repeats into a small protein of known structure made it associate irreversibly into oligomers. That association took place during the folding of the protein molecules and led to their becoming firmly interlocked by either strand- or domain-swapping. Thermodynamic considerations suggest that elongation of glutamine repeats beyond a certain length may lead to a phase change from random coils to hydrogen-bonded hairpins. Possible mechanisms of expansion of CAG repeats are discussed in the light of looped DNA model structures. 相似文献
5.
Gangliosides with a short carbohydrate chain: II3(NeuAc)2-LacCer, II3(NeuAc)2-GgOse3Cer, II3(NeuAc)3-LacCer, II3NeuAc-LacCer, and II3NeuAC-GgOse3 Cer, were found to be predominant in the brain of 8 species of cartilaginous fish, elasmobranches. N-acetylneuraminic acid was the only sialic acid found in these gangliosides, the N-glycolyl derivative being practically absent. 4-Sphingenine was shown to be the predominant sphingoid in elasmobranch brain gangliosides. The sequential enzymatic hydrolysis of II3(NeuAc)2 -LacCer from shark and ray brain by acylneur-aminyl hydrolase (EC 3.2.1.18) and β-D-galactoside-galactohydrolase (EC 3.2.1.23), as well as permethylation studies, provide further evidence for the following structure of this major elasmobranch brain ganglioside: 相似文献
6.
G P Obukhova S G Seliverova E I Varlinskaia T V Avaliani N S Abdaladze V A Ter-Karapenian O V Bogdanov 《Zhurnal evoliutsionno? biokhimii i fiziologii》1992,28(4):510-517
Morphological quantitative and qualitative analysis of the pyramidal neurones in the motor cortex of rat puppies after administration of the blood serum from human donors with central motor disorders reveals the dependence of the quality and quantity of neurones from the effect of corresponding blood sera. Pathologic blood serum decreases the number and induces degradation of dendritic organization of the pyramidal neurones. The effect of the blood sera on quantitative and qualitative properties of the pyramidal neurones in rat puppies depends on the age of donor infants with central motor disorders. Blood serum from newborn babies with motor dysfunctions significantly decreases the number of labeled pyramidal neurones and results in degradation of dendritic organization, whereas sera from 11-13-year infants only insignificantly affect these characteristics. 相似文献
7.
I P Ashmarin M F Obukhova A A Mart'ianov R A Danilova N E Babskaia Z I Storozheva G K Grechko N V Kuznetsova 《Nauchnye doklady vysshe? shkoly. Biologicheskie nauki》1991,(3):15-24
The active immunization of rabbits and white rats to antidepressant sydnophen results in the formation of antibodies binding norepinephrine, dophamine, serotonine as well peptide regulatory compounds: substance P, pynorphine, vasopressin and beta-endorphin. The immunization against endogenic antidepressant thyroliberin induces the formation of antibodies to the same biogenic amines and to the gamma-aminobutyric acid, oxytocin and leu encephalin. The data obtained are discussed in connection with some physiological and biochemical changes found earlier during immunization to antidepressants. 相似文献
8.
9.
Using a battery of seven lectin-ferritin conjugates as probes for cell surface glycoconjugates, we have studied the pattern of plasmalemmal differentiation of cells in the embryonic rat pancreas from day 15 in utero to the early postpartum stage. Our results indicate that differentiation of plasmalemmal glycoconjugates on acinar, endocrine, and centroacinar cells is temporally correlated with development and is unique for each cell type, as indicated by lectin-ferritin binding. Specifically, (a) expression of adult cell surface saccharide phenotype can be detected on presumptive acinar cells as early as 15 d in utero, as indicated by soybean agglutinin binding, and precedes development of intracellular organelles characteristic of mature acinar cells; (b) maturation of the plasmalemma of acinar cells is reached after intracellular cytodifferentiation is completed, as indicated by appearance of Con A and fucoselectin binding sites only at day 19 of development; conversely, maturation of the endocrine cell plasmalemma is accompanied by "loss" (masking) of ricinus communis II agglutinin receptors; and (c) binding sites for fucose lectins and for soybean agglutinin are absent on endocrine and centroacinar cells at all stages examined. We conclude that acinar, centroacinar, and endocrine cells develop from a common progenitor cell(s) whose plasmalemmal carbohydrate composition resembles most closely that of the adult centroacinar cell. Finally, appearance of acinar lumina beginning at approximately 17 d in utero is accompanied by differenetiation of apical and basolateral plasmalemmal domains of epithelial cells, as indicated by enhanced binding of several lectin-ferritin conjugates to the apical plasmalemmal, a pattern that persists from this stage through adult life. 相似文献
10.
L N Gavrilova A I Mikha?lov G P Obukhova M M Khanaishvili 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1977,27(1):73-80
A local pathological inert motor reaction, involving a forced flexion of the forepaw, was formed after simultaneous stimulation with NaCl solution of a part of the tongue brought out to the cheek and electrical stimulation of the forepaw. The reaction decreased (by 70 to 80%) after electrical stimulation of the dorsal hippocampus (beyond CA3). At the same time the animal's emotional stress diminished, as evidenced by the reduced heart rate and a reduced theta-rhythm in the hippocampus. 相似文献