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961.
We recently reported a beta-peptide foldamer, beta53-1, that folds into a 14-helix in aqueous solution, binds the oncoprotein hDM2 with submicromolar affinity, and potently inhibits the interaction of hDM2 with a peptide derived from the activation domain of p53 (p53AD). Here, we present the solution structure of beta53-1 in methanol. Details of the structure illustrate fundamental and novel elements of beta-peptide folding and recognition. These elements include the detailed arrangement of a complex, 14-helix-stabilizing salt bridge on one helical face, and a unique "wedge into cleft" packing interaction along a second. The structure also reveals how a subtle distortion in the beta53-1 14-helix geometry alters the presentation of its recognition epitope, rendering it particularly well suited for alpha-helix mimicry. The solution structure of beta53-1 demonstrates that well folded beta-peptide oligomers can effectively present an extended, highly variable surface that could be used as a general platform for targeting critical protein-protein interfaces. 相似文献
962.
E. N. Fedoseeva A. V. Budruev L. A. Smirnova Yu. D. Semchikov V. B. Fedoseev 《Polymer Science Series A》2007,49(8):868-875
It has been shown that the interaction of chitosan and oligochitosan with unsaturated acrylic esters via the nucleophilic addition mechanism and their condensation with heptadecyl isocyanate yield hydrophobic alkyl-containing derivatives of the above polymers. The method of modification of oligochitosan in reactions via end functional groups is developed. 相似文献
963.
Fluorescence, whose spectral and magnetic properties permit its assignment to the luminescence of a triplex exciplex, has been discovered at times 3 sec after photoexcitation in the luminescence spectrum of the pyrene+N,N-diethylaniline system in methanol at 600 nm by the method of nanosecond stroboscopic fluorometry.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 25, No. 5, pp. 623–626, September–October, 1989. 相似文献
964.
The composition is given of the fatty acids of the red marine algaPalmaria stenogona. The amount of eicosapentaenoic acid (EPA) in the alga was 69.9–77.0% of the total fatty acids. The procedure for isolating
EPA of 80–90% purity from the alga is described which includes the saponification of the algal lipids, the selective extraction
of the unsaponifiable lipids, the isolation of the free fatty acids, and their separation by the method of crystallizing inclusion
complexes of the fatty acids with urea.
Institute of Marine Biology, Far Eastern Branch, USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh
Soedinenii, No. 3, pp. 330–333, May–June, 1990. 相似文献
965.
D ← X resonance enhanced three-photon excitation spectrum of iodine was observed by a cw intracavity absorption technique. Vibrational quantum numbers of D ← X transitions are given for every major spectral feature. The corresponding one-photon enhancement from the B state is evident from the one-photon vibrational assignment. The spectroscopic constants for the D state are v00 = 40 998 cm?1 ω′0 = 113 cm?1 and ω′0χ′0 = 0.045 cm?. 相似文献
966.
E. Toromanoff 《Tetrahedron》1978,34(11):1665-1673
To take place stereoselectively SN2' reactions of cyclohexene derivatives require an axial leaving group either on a half-chair (suprafacial reaction) or on a 1,3-diplanar form or a boat (antarafacial reaction). These conclusions appear generally relevant to concerted reactions of cyclohexenic derivatives involving an allylic migration of the olefinic bond. 相似文献
967.
H. E. Zaugg J. E. Leonard R. W. Denet D. L. Arendsen 《Journal of heterocyclic chemistry》1974,11(5):797-802
The previously discovered neighboring group reaction has been extended to the synthesis of chroman derivatives (i.e., 4, 5, 6) containing geminal methyls in the 2-position, a feature common to certain physiologically active natural chromans. In two instances, cyclic ortho ester by-products (8), not observed in previous work, were formed as a result of the intramolecular trapping of tetrahedral intermediates. Reasons for the incursion of this unexpected side reaction are discussed. 相似文献
968.
The mixed oxide system Cr2O3? MnOx (2 ≥ x ≥ 1.5) was investigated by X-ray diffraction, by measurements of magnetic susceptibility, and by chemical determination of excess oxygen (BUNSEN'S method). The Presence of the antiferromagnetic oxides Cr2O3, β-MnO2, α-Mn2O3 and a ferromagnetic phase Cr1?yMnyO2 was stated. The formation of the latter with fourvalent chromium is explained by a lattice induction effect of the MnO2 (rutile type). 相似文献
969.
The photoelectron spectra of the six propellanes 1 to 6 have been recorded. Those bands which correspond to ejection of an electron from a π-orbital have been assigned, using the concept of through bond and through space interaction. Homoconjugative interaction between the π-systems of the two butadiene moieties of 6 is of the same order as that of the π-orbitals in norbornadiene. 相似文献
970.
1 newly-discovered method of synthesizing PGE1 (prostaglandin E1) is explained and diagrammed chemically. Recrystallization of the synthetic product produced material identical in all respects with natural PGE1. The synthetic product showed the same infrared spectrum and chromatographic values as racemic and natural forms of PGE1. The biological activity of the synthetic product was found to be .1% of that of the naturally-occurring PGE1 in the stimulation of smooth muscle contraction. This is the 1st report of a total synthesis of PGE1. Research continues on improvements in this synthesizing method and on discovering other synthetic approaches to PGs. 相似文献