排序方式: 共有32条查询结果,搜索用时 15 毫秒
1.
O V Salamakha N P Rogatykh I V Savochkina L A Tikhomirova I L Bazarenko 《Mikrobiologiia》1989,58(5):778-784
The mycelium of Streptomyces fradiae was fractionated by differential centrifugation in a sucrose density gradient (SDG) using various samples of the inoculation material and aliquots of the cultural broth taken in the course of tylosin production. The mode of mycelium distribution in SDG made it possible to select the most active inoculation material. The mycelium was redistributed from sucrose layers with a high density to those with a lower density in the course of fermentation. The fractions differed in the antibiotic activity but none of them had an activity higher than in the control centrifuged in 30% sucrose and washed off just like the fractions. Therefore, mycelium fractionation in SDG would not elevate its antibiotic activity. The paper presents the cytological characteristics of different fractions changing in the course of fermentation. 相似文献
2.
T V Sviriaeva L P Savochkina V V Gorn R Sh Bibilashvili 《Molekuliarnaia biologiia》1988,22(1):131-138
Sanger method was modified to fulfill the requirements of sequencing of oligodeoxyribonucleotides. E. coli DNA polymerase I Klenow fragment was used for all the reactions. The method consists of three steps made in succession in one tube: 1. Optional hydrolysis of a 5'-labeled oligodeoxyribonucleotide primer in order to get a set of primers of different lengths. 2. Elongation of the produced set of primers in the presence of a template, natural dNTPs and chain terminating dNTP analogs. 3. Hydrolysis of the products of the previous step in order to remove the unterminated molecules. Change of steps in achieved just by varying the reaction conditions without any product purification. The method in insensitive to the presence of admixture of oligonucleotides which is not complementary to the primer or to the template. 相似文献
3.
Strong early bacteriophage T7 promoters A2 and A3 and also A2 and lac UV5 promoters with altered segments downstream the initiation of RNA start point were cloned using specially constructed plasmid vectors pBRS188 and PBRS240. The relative signal strengths of these promoters in vivo and in vitro were evaluated and the kinetic parameters of their interaction with RNA polymerase were determined. It has been shown that the nucleotide sequence of the transcribed region plays a significant role in specific promoter-RNA polymerase interaction and that the rate-limiting step of RNA synthesis initiation is different for various promoters. 相似文献
4.
Belyanko T. I. Feoktistova E. S. Skrypina N. A. Skamrov A. V. Gurskii Ya. G. Rutkevich N. M. Dobrynina N. I. Bibilashvilli R. Sh. Savochkina L. P. 《Biophysics》2019,64(3):331-338
Biophysics - Abstract—Variants of miniplasminogen with an altered primary structure have been designed to study previously described changes in tryptophan fluorescence during plasminogen... 相似文献
5.
Alekseenkova VA Belianko TI Timofeeva AV Savochkina LP Heumann H Bibilashvili RSh 《Molekuliarnaia biologiia》2001,35(5):879-899
The kinetic characteristics have been studied for noncircularly permuted variants of the human hepatitis delta virus (HDV) antigenomic ribozyme to find out the cause of the two-phase kinetics of the self-cleavage reaction. Different ways of reaction initiation, suboptimal conditions, and jumpwise changes of reaction conditions have been used, and the temperature dependences have been studied. A correlation has been shown between the apparent kinetic constant of the first reaction phase and the portion of the ribozyme molecules that self-cleaved during the first phase. Partial restoration of the initial reaction characteristics has been shown by the reinitiation of reaction being stopped after completing the first phase. On the basis of all the data obtained, a scheme of the self-cleavage reaction has been proposed including: (i) activation of the ribozyme with energy of 40-50 kcal/mol and a characteristic time of several deciminutes under optimal reaction conditions; (ii) fast and reversible reaction of the phosphodiester bond cleavage; (iii) reaction leading to isomerization of the 3',5'-phosphodiester bond to the 2',5' bond in the self-cleavage site with a characteristic activation time of tens of minutes; and (iv) practically irreversible conformational change leading to fixation of the cleavage by immobilization of the 5'-terminal nucleotide of the product in the center of the formed structure and displacement of the 3'-terminal nucleotide to the periphery. The latter process has a characteristic time of tens of minutes and a low activation energy. 相似文献
6.
Alovskaia AA Safronova VG Kornilov VV Kornev AN Savochkina IuM Kraupenhaar R Betzel K Voelter W Mikhaĭlov AM 《Biofizika》2000,45(4):688-694
The ability of viscum at different concentrations to modulate the respiratory burst in neutrophils, induced by the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine was studied. This does not exclude the possibility that viscum can interact with the receptor of this peptide. The analysis of the primary structure of viscum revealed elements structurally analogous to the chemotactic peptide. It is assumed that viscum can exhibit the properties an antagonist of the receptor of N-formyl-methionyl-leucyl-phenylalanine, and the mechanism of action of viscum depends on its concentration. 相似文献
7.
L P Savochkina V O Retchinsky R S Beabealashvilli 《Molecular & general genetics : MGG》1983,189(1):142-147
Strong bacteriophages lambda and T7 promoters for Escherichia coli RNA polymerase were cloned in a multicopy plasmid. To achieve this result, two variants of the promoter-probe vectors were constructed. It was found that (i) modifications of the nucleotide sequence, apart from the commonly accepted promoter region, both upstream and downstream of the RNA initiation point greatly influenced the efficiency of promoters in vivo, (ii) a recombinant DNA composed of one of the promoter-probe plasmids and a tandem of A1, A2, and A3 promoters of T7 bacteriophage DNA induced a reproducible secondary change in plasmid DNA upon cloning. This change was substitution of the part of the recombinant that originated as T7 by a large portion of the host DNA. 相似文献
8.
L P Savochkina T V Sviriaeva L N Be?gel'man N Sh Padiukova D A Kuznetsov Iu P Lysov S N Mikha?lov R Sh Bibilashvili 《Molekuliarnaia biologiia》1989,23(6):1700-1710
2 theta-C-methyl substituted and phosphonate analogs of UTP were prepared and together with the synthesized earlier 3'-C-methyl-UTP were investigated in the RNA synthesis reaction catalysed by Escherichia coli RNA-polymerase. Substrate properties of UTP analogs were studied in the presence of all natural triphosphates, in the absence of UTP and under conditions of soil substrate reaction. It was shown that UTP(3'CH3) is incorporated into the RNA chain and terminates further RNA elongation. Another analog UTP (2'CH3) may substitute natural UTP in RNA synthesis, but the effectivity of its incorporation is diminished. Phosphonate analog UTP(5'CH2) is a pseudoterminator of RNA synthesis. The conformational analysis of 2'- and 3'C-methylnucleosides by force-field method of calculation was carried out in order to find energetically forbidden conformations of these analogs due to the collision of bulky methyl group and a heterocyclic base. An attempt was made to fix the conformation of the substrate during its enzymatic transformation. 相似文献
9.
10.
A new plasmid vector, designated pBRS188 has been constructed for cloning of promoter-containing DNA fragments. This plasmid is a derivative of the E. coli drug-resistance plasmid pBR322 in which a small region (13 base pairs long) within the Tc promoter is eliminated. As a result of the alteration pBRS188 has lost the ability to confer Tc resistance to the host strain. Cloning of foreign DNA fragments, carrying promoters for E. coli RNA polymerase, into the unique EcoRI site of pBRS188 allows to isolate the recombinant TcR transformants. Our construction required the use of new techniques, involving partial hydrolysis of DNA fragments by E. coli DNA polymerase I in the presence of one deoxyribonucleosidetriphosphate and by nuclease S1. An important feature of this method is the ability to regenerate restriction endonuclease recognition sites at junctions of DNA fragments. 相似文献