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Triple-helical Structure (triple-helical + structure)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

Optimization of Triple-Helix-Directed DNA Cleavage by Benzoquinoquinoxaline,Ethylenediaminetetraacetic Acid Conjugates

CHEMBIOCHEM, Issue 9 2003
Rula Zain Dr.
Abstract The formation of triple-helical structures of DNA is based on sequence-specific recognition of oligopyrimidine,oligopurine stretches of double-helical DNA. Triple-helical structures can be stabilized by DNA-binding ligands. Benzoquinoquinoxaline (BQQ) derivatives are among the most potent intercalating-type agents known to stabilize DNA triple-helical structures. We previously reported the conversion of BQQ into a triplex-directed DNA cleaving agent, namely BQQ,ethylenediaminetetraacetic acid (EDTA), by coupling of 6-(3-aminopropylamino)BQQ to a suitable ethylenediaminetetraacetic acid derivative, and we demonstrated the ability of this conjugate to cause double-stranded cleavage of DNA at the triplex site. However, this prototype derivative BQQ,EDTA conjugate showed lower affinity towards triplex DNA than BQQ itself. In the light of this observation, and guided by molecular modeling studies, we synthesized a second generation of BQQ,EDTA conjugates based on 6-[bis(2-aminoethyl)amino]- and 6-(3,3,-diamino- N -methyldipropylamino),BQQ derivatives. We confirmed by DNA melting experiments that the new conjugates displayed an increased specific affinity towards triple helices when compared to the previously synthesized BQQ,EDTA. In addition, the efficiency of these new agents in triplex-specific binding and cleavage was demonstrated by triplex-directed double-stranded cleavage of plasmid DNA. [source]

Complete primary structure of rainbow trout type I collagen consisting of ,1(I),2(I),3(I) heterotrimers

FEBS JOURNAL, Issue 10 2001
Masataka Saito
The subunit compositions of skin and muscle type I collagens from rainbow trout were found to be ,1(I),2(I),3(I) and [,1(I)]2,2(I), respectively. The occurrence of ,3(I) has been observed only for bonyfish. The skin collagen exhibited more susceptibility to both heat denaturation and MMP-13 digestion than the muscle counterpart; the former had a lower denaturation temperature by about 0.5 °C than the latter. The lower stability of skin collagen, however, is not due to the low levels of imino acids because the contents of Pro and Hyp were almost constant in both collagens. On the other hand, some cDNAs coding for the N-terminal and/or a part of triple-helical domains of pro,(I) chains were cloned from the cDNA library of rainbow trout fibroblasts. These cDNAs together with the previously cloned collagen cDNAs gave information about the complete primary structure of type I procollagen. The main triple-helical domain of each pro,(I) chain had 338 uninterrupted Gly-X-Y triplets consisting of 1014 amino acids and was unique in its high content of Gly-Gly doublets. In particular, the bonyfish-specific ,(I) chain, pro,3(I) was characterized by the small number of Gly-Pro-Pro triplets, 19, and the large number of Gly-Gly doublets, 38, in the triple-helical domain, compared to 23 and 22, respectively, for pro,1(I). The small number of Gly-Pro-Pro and the large number of Gly-Gly in pro,3(I) was assumed to partially loosen the triple-helical structure of skin collagen, leading to the lower stability of skin collagen mentioned above. Finally, phylogenetic analyses revealed that pro,3(I) had diverged from pro,1(I). This study is the first report of the complete primary structure of fish type I procollagen. [source]

Thermosensitive gel formation of novel polypeptides containing a collagen-derived Pro-Hyp-Gly sequence and an elastin-derived Val-Pro-Gly-Val-Gly sequence

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2005
Yasushi Morihara
Abstract A triple-helix-forming collagen model peptide, (prolyl- trans -4-hydroxyprolyl-glycyl)10 [(Pro-Hyp-Gly)10], and a thermosensitive elastin-derived pentapeptide, valyl-prolyl-glycyl-valyl-glycyl (Val-Pro-Gly-Val-Gly), were copolymerized in various mole ratios using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride and 1-hydroxybenzotriazole in dimethyl sulfoxide at 20 °C. All of the obtained polypeptides have molecular weight higher than 103 and contain a triple-helical structure, and showed an inverse phase transition from transparent solution to turbid suspension in response to a rise in temperature. The lower critical solution temperature of the polypeptide solution decreased upon increasing the content of Val-Pro-Gly-Val-Gly. Furthermore, polypeptides containing 82,86 mol % of Val-Pro-Gly-Val-Gly in composition showed reversible gel formation, suggesting that (Pro-Hyp-Gly)10 acts as a hydrated unit and Val-Pro-Gly-Val-Gly acts as a thermosensitive crosslinking point. These biodegradable thermosensitive polypeptides may be useful for biomedical applications, including, as a scaffold for tissue regeneration. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6048,6056, 2005 [source]