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排序方式: 共有433条查询结果,搜索用时 359 毫秒
1.
E. P. Isakova Yu. I. Deryabina N. N. Gessler T. A. Belozerskaya Ya. M. Rabinovich 《Applied Biochemistry and Microbiology》2010,46(3):318-323
Cell respiratory activity of protoplasts obtained from the wild type of Neurospora crassa and photoreceptor complex WCC—white collar 1 (wc-1) and white collar 2 (wc-2)—mutants of Neurospora crassa strains was investigated. Respiration inhibition by KCN in the presence of 25 mM succinate was similar in all strains and
did not exceed 83–85% against control. The significant induction of KCN-resistant respiratory pathway occurred under 1% glucose
oxidation in wc-1 and wc-2 mutants if compared with the wild type strains. The inhibitors of the main (cytochrome) pathway of electron transfer in mitochondria—1
mM KCN and antimycin A (4 μg/ml)—blocked the respiration rate of the protoplasts from N. crassa wild type by 75%, while the cell respiration of wc-1 and wc-2 strains was suppressed by approximately 50%. The specific inhibitor of alternative oxidase—10 mM salicylhydroxamic acid (SHAM)—in
combination with the blockers of mitochondrial electron transfer chain caused the total suppression of respiratory activity
of protoplasts in all studied strains. It is supposed that an increase of KCN-resistance in WCC mutants under glucose oxidation
is connected with alternative oxidase activation as the result of failure in reception and signal transduction of active oxygen
species. 相似文献
2.
M. L. Rabinovich 《Applied Biochemistry and Microbiology》2006,42(1):1-26
Development of national research of cellulose-degrading microorganisms and enzymes is reviewed, with emphasis on the prospects of producing ethanol from cellulose materials using cellulolytic enzymes. Leading Russian research groups in this field are introduced. A section of the review analyzes problems and prospects of setting up environmentally friendly production of motor biofuels from renewable raw materials of plant origin (an approach developed in Russia). 相似文献
3.
W N Hunter T Brown G Kneale N N Anand D Rabinovich O Kennard 《The Journal of biological chemistry》1987,262(21):9962-9970
The structure of the deoxyoligomer d(C-G-C-G-A-A-T-T-T-G-C-G) was determined at 2.5-A resolution by single crystal x-ray diffraction techniques. The final R factor is 18% with the location of 71 water molecules. The oligomer crystallizes in a B-DNA-type conformation, with two strands interacting to form a dodecamer duplex. The double helix consists of four A X T and six G X C Watson-Crick base pairs and two G X T mismatches. The G X T pairs adopt a "wobble" structure with the thymine projecting into the major groove and the guanine into the minor groove. The mispairs are accommodated in the normal double helix by small adjustments in the conformation of the sugar phosphate backbone. A comparison with the isomorphous parent compound containing only Watson-Crick base pairs shows that any changes in the structure induced by the presence of G X T mispairs are highly localized. The global conformation of the duplex is conserved. The G X T mismatch has already been studied by x-ray techniques in A and Z helices where similar results were found. The geometry of the mispair is essentially identical in all structures so far examined, irrespective of the DNA conformation. The hydration is also similar with solvent molecules bridging the functional groups of the bases via hydrogen bonds. Hydration may be an important factor in stabilizing G X T mismatches. A characteristic of Watson-Crick paired A X T and G X C bases is the pseudo 2-fold symmetry axis in the plane of the base pairs. The G X T wobble base pair is pronouncedly asymmetric. This asymmetry, coupled with the disposition of functional groups in the major and minor grooves, provides a number of features which may contribute to the recognition of the mismatch by repair enzymes. 相似文献
4.
Based on 4-methylcoumarinyl-7-amide (Amc) arginine and a series N-alkyloxycarbonyl derivatives of phenylalanine, eleven Amc-derivatives of the type ROCO-Phe-Arg-Amc (R = alkyl) were synthesized; also were n-C3H7OCO-Leu-Arg-Amc and n-C3H7OCO-D-Phe-Arg-Amc synthesized. The enzymatic hydrolysis of these compounds under the action of tissue and plasma human kallikreins were studied. Tissue kallikrein from human urine hydrolyzed the compounds with R = n-propyl and n-butyl and n-C3H7OCO-Leu-Arg-Amc more readily than the known substrates Z-Phe-Arg-Amc and H-Pro-Phe-Arg-Amc. n-C3H7OCO-D-Phe-Arg-Amc is a weak inhibitor of this enzyme (Ki = 1.5.10(-4) M). Human plasma kallikrein hydrolyzed these novel substrates at a lower rate than Z-Phe-Arg-Amc. 相似文献
5.
Refined crystal structure of an octanucleotide duplex with G . T mismatched base-pairs 总被引:9,自引:0,他引:9
W N Hunter G Kneale T Brown D Rabinovich O Kennard 《Journal of molecular biology》1986,190(4):605-618
Single crystal X-ray diffraction techniques have been used to determine the structure of the DNA octamer d(G-G-G-G-C-T-C-C) at a resolution of 2.25 A. The asymmetric unit consists of two strands coiled about each other to produce an A-type DNA helix. The double helix contains six G . C Watson-Crick base-pairs and two G . T mismatched base-pairs. The mismatches adopt a "wobble" type structure in which both bases retain their major tautomer forms. The double helix is able to accommodate this G . T pairing with little distortion of the overall helical conformation. Crystals of this octamer melt at a substantially lower temperature than do those of a related octamer also containing two G . T base-pairs. We attribute this destabilization to disruption of the hydration network around the mismatch site combined with changes in intermolecular packing. Full details are given of conformational parameters, base stacking, intermolecular contacts and hydration involving 52 solvent molecules. 相似文献
6.
Ordered water structure in an A-DNA octamer at 1.7 A resolution 总被引:5,自引:0,他引:5
O Kennard W B Cruse J Nachman T Prange Z Shakked D Rabinovich 《Journal of biomolecular structure & dynamics》1986,3(4):623-647
The crystal structure of the deoxyoctamer d(G-G-Br U-A-BrU-A-C-C) was refined to a resolution of 1.7 A using combined diffractometer and synchrotron data. The analysis was carried out independently in two laboratories using different procedures. Although the final results are identical the comparison of the two approaches highlights potential problems in the refinement of oligonucleotides when only limited data are available. As part of the analysis the positions of 84 solvent molecules in the asymmetric unit were established. The DNA molecule is highly solvated, particularly the phosphate-sugar back-bone and the functional groups of the bases. The major groove contains, in the central BrU-A-BrU-A region, a ribbon of water molecules forming closed pentagons with shared edges. These water molecules are linked to the base O and N atoms and to the solvent chains connecting the O-1 phosphate oxygen atoms on each strand. The minor groove is also extensively hydrated with a continuous network in the central region and other networks at each end. The pattern of hydration is briefly compared with that observed in the structure of a B-dodecamer. 相似文献
7.
8.
It was shown that 7-amino-4-methylcoumarin (MC-amine), resulted from the enzymatic hydrolysis of 4-methylcoumaryl-7-amide (MC-amide) peptide substrates, may be estimated not only fluorometrically but also photometrically. A photometric method for estimating activity of tissue kallikrein (EC 3.4.21.35) and urokinase (EC 3.4.21.31) is suggested using Z-Phe-Arg-NHMC and Z-Gly-Gly-Arg-NHMC, respectively, as substrates. Kinetic parameters of the enzymatic hydrolysis, as obtained by photometric and fluorometric detection of the MC-amine formed, were in good agreement. The differential coefficient of molar extinction of the substrates and MC-amine at 360 nm was found to be 10,800 M-1 cm-1. 相似文献
9.
The ATP-binding-cassette transmembrane transporters (ABC transporters)
known from vertebrates belong to four major subfamilies: (1) the P-
glycoproteins (Pgp); (2) the cystic fibrosis transmembrane conductance
regulators (CFTR); (3) the Tap proteins encoded with the major
histocompatibility complex of mammals; and (4) the peroxisomal membrane
proteins. Both Pgp and CFTR have a structure suggesting a past internal
gene duplication; a phylogenetic analysis indicated that these duplications
occurred independently, while an independent tandem gene duplication
occurred in the case of the Tap family. Both the Pgp and Tap proteins show
evidence of relationship to bacterial ABC transporters lacking internal
duplication, and both are significantly more closely related to the HlyB
and MsbA families of transporters from purple bacteria than they are to ABC
transporters from nonpurple bacteria. The simplest hypothesis to explain
this observation is that eukaryotic Pgp and Tap genes are descended from a
mitochondrial gene or genes that were subsequently translocated to the
nuclear genome. The Pgp genes of eukaryotes are characterized by a
remarkable degree of convergent evolution between the ATP-binding cassettes
of their N- terminal and C-terminal halves, whereas no such convergence is
seen between the two halves of CFTR genes or between the duplicated Tap
genes. Exon 13 of the CFTR gene, which encodes a putative regulatory domain
not found in other ABC transporters apart from CFTR, showed high levels of
both synonymous and nonsynonymous difference in comparisons among different
mammalian species, suggesting that this region is a mutational hot spot.
相似文献
10.