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A chemical approach to studies of the three-dimensional structure of tRNA - alkylation with a reagent covalently bound to a "peculiar site''. 总被引:2,自引:1,他引:1
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Yeast valine tRNA1 was chemically modified with chlorambucil N-hydroxysuccinimide ester. tthe reagent was attached covalently to the valine residue of valyl-tRNA1Val under the conditions which prevented tRNA from alkylation. Chlorambucilyl-valyl-tRNA1Val thus obtained was separated from excess reagent and incubated in an aqueous solution at neutral pH in the presence of Mg++ions. Highly efficient intramolecular self-alkylation of chlorambucilyl-valyl-tRNA1Val took place. The chlorambucil residue bound covalently to the amino group of the valine residue of tRNA1Val alkylates the 5'-terminal phosphate group of the molecule, and its 3'-terminal sequence -A-C-C-A. 相似文献
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Sequence-specific chemical modification of a 365-nucleotide-long DNA fragment with an alkylating oligonucleotide derivative 总被引:2,自引:0,他引:2
An aromatic 2-chloroethylamino group was attached to the 5'-terminal phosphate of the oligodeoxyribonucleotide pCCCTCTTTCTT. The oligonucleotide derivative prepared was used for modification of the 365-nucleotide-long DNA fragment. It was found that modification of the fragment proceeds in a sequence-specific way at 3 guanosine residues within the sequence complementary to the oligonucleotide reagent. 相似文献
88.
Effect of Enzyme Preparation from the Marine Mollusk Littorina kurila on Fucoidan from the Brown Alga Fucus distichus 总被引:1,自引:0,他引:1
Bilan MI Kusaykin MI Grachev AA Tsvetkova EA Zvyagintseva TN Nifantiev NE Usov AI 《Biochemistry. Biokhimii?a》2005,70(12):1321-1326
A fucoidanase preparation from the marine mollusk Littorina kurila cleaved some glycosidic bonds in fucoidan from the brown alga Fucus distichus, but neither fucose nor lower oligosaccharides were produced. The main product isolated from the incubation mixture was a polysaccharide built up of disaccharide repeating units -->3)-alpha-L-Fucp-(2,4-di-SO3(-))-(1-->4)-alpha-L-Fucp-(2SO3(-))-(1-->, the structure coinciding with the idealized formula proposed for the initial substance. A polymer fraction with the same carbohydrate chain but sulfated only at positions 2 and nonstoichiometrically acetylated at positions 3 and 4 of fucose residues was isolated as a minor component. It is suggested that the native polysaccharide should contain small amounts of non-sulfated and non-acetylated fucose residues, and only their glycosidic bonds are cleaved by the enzyme. The enzymatic hydrolysis showed that irregular regions of the native polysaccharide containing acetylated and partially sulfated repeating units were assembled in blocks. 相似文献
89.
The synthesis of a biotinylated derivative of dCTP, viz. N4-[(N-biotinyl)-4-amino-butoxyl]-2'-deoxycytidine 5'-triphosphate (I), is described. DNA polymerase I (Klenow fragment) incorporates (I) in DNA chains instead of thymidine, although with a lower efficiency than previously described biotinylated dUTP derivative (II), whereas highly purified DNA polymerase alpha from human placenta uses as substrate derivative (II) but not (I). A DNA fragment bearing biotin residues in one of strands was synthesized with the use of DNA polymerase alpha and dUTP derivative (II); its cloning in the plasmid vector pBR322 revealed that the DNA nucleotide sequence remained intact. 相似文献
90.
Gerbst AG Grachev AA Ustiuzhanina NE Khatuntseva EA Tsvetkov DE Usov AI Shashkov AS Preobrazhenskaia ME Ushakova NA Nifant'ev NE 《Bioorganicheskaia khimiia》2004,30(2):156-167
A series of selectively sulfated di- and trisaccharide derivatives corresponding to the potential fragments of fucoidans with a (1-->2)-alpha-bound fucobioside unit were synthesized and studied by 1H and 13C NMR spectroscopy. NOE experiments and molecular modeling were used for a conformational analysis of the compounds synthesized. In the case of disaccharides, the experimental NOE values were found to agree with those obtained using modeling with the use of density functional theory (DFT) and differ from those resulting from modeling by the molecular mechanics MM3 force field. Trisaccharide fragments partially or completely sulfated in position 4 turned out to be correctly described by both MM3 force field and DFT computation. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 2; see also http://www.maik.ru. 相似文献