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1.
5‐Amino‐4‐methyl‐2‐phenyl‐6‐substitutedfuro[2,3‐d]pyrimidines ( 2a‐c ) were reacted with 2,5‐dimethoxytetrahydrfuran to afford the pyrrolyl derivatives 3a‐c . Compound 3a was chosen as intermediate for the synthesis of poly fused heterocycles incorporated furopyrimidines moiety 4–11 . Some of the synthesized compounds were screened for their antibacterial and antifungal activities. 相似文献
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3.
[structure: see text] We report an initial step toward the development of sulfonamide-based complements for extended peptide strands. A molecule containing one secondary sulfonamide unit and one valine residue linked by a turn-forming segment was found by IR and NMR to exhibit a doubly hydrogen-bonded folding pattern in chloroform. 相似文献
4.
Sadowsky JD Schmitt MA Lee HS Umezawa N Wang S Tomita Y Gellman SH 《Journal of the American Chemical Society》2005,127(34):11966-11968
Molecules that bind to specific surface sites on proteins are of great interest from both fundamental and practical perspectives. We are exploring a ligand development strategy that is based on oligomers with discrete folding propensities ("foldamers"); we target a specific cleft on the cancer-associated protein Bcl-xL because this system is well characterized structurally. In vivo, this cleft binds to alpha-helical segments (BH3 domains) of other proteins. We evaluated several types of helical foldamer, built entirely from beta-amino acid residues or from mixtures of alpha- and beta-amino acid residues, and ultimately identified foldamers in the latter class that bind very tightly to Bcl-xL. Our results suggest that combining different types of foldamer backbones will be an effective and general strategy for creating high-affinity and specific ligands for protein surface sites. 相似文献
5.
In situ derivatization of a variety of alpha-substituted aldehydes via reaction with chiral amines allows convenient and efficient determination of enantiomeric excess. (1)H NMR analysis of the imine diastereomer ratio can be conducted immediately after the aldehyde and amine have been mixed. The results correlate well with ee values determined by more traditional (and slower) methods. This approach may be broadly applicable to alpha-substituted aldehydes. [reaction: see text] 相似文献
6.
Horvath JD Koritnik A Kamakoti P Sholl DS Gellman AJ 《Journal of the American Chemical Society》2004,126(45):14988-14994
Kinked-stepped, high Miller index surfaces of metal crystals are chiral and, therefore, exhibit enantiospecific properties. Previous temperature-programmed desorption (TPD) spectra have shown that the desorption energies of R-3-methylcyclohexanone (R-3-MCHO) on the chiral Cu(643)(R) and Cu(643)(S) surfaces are enantiospecific (J. Am. Chem. Soc. 2002, 124, 2384). Here, a comparison of the TPD spectra from Cu(111), Cu(221), Cu(533), Cu(653)(R&S), and Cu(643)(R&S) surfaces reveals that the enantiospecific desorption occurs from the chiral kink sites on the Cu(643) surfaces. Titration of the chiral kink sites with I atoms confirms this assignment of desorption features in the TPD spectra. Finally, the enantiospecific difference in the desorption energies of R- and S-3-MCHO has been used as the basis for demonstration of an enantioselective, kinetic separation of racemic 3-MCHO into its purified components during adsorption and desorption on the Cu(643)(R&S) surfaces. 相似文献
7.
Braverman Michael SH.; Stepanov Vladimir D. 《Bulletin London Mathematical Society》1994,26(3):283-287
Necessary and sufficient conditions for the boundedness of thediscrete Hardy operator of the form , from to when 0 < q < 1 <p , is given. 相似文献
8.
Woll MG Fisk JD LePlae PR Gellman SH 《Journal of the American Chemical Society》2002,124(42):12447-12452
A stereoselective synthetic route is reported for the introduction of side chains at the 3-position of trans-2-aminocyclopentanecarboxylic acid (ACPC). Ring opening of the aziridine 2-benzyloxymethyl-6-azabicyclo[3.1.0]hexane with selected nucleophiles occurs in a regioselective manner and provides ACPC precursors with functional groups at the 3-position, trans to the 2-amino group. Oligomers composed of the 3-substituted ACPC residues maintain the 12-helical conformation displayed by the nonsubstituted analogues, as shown by their similar circular dichroism signatures. The added diversity of the new residues provides good dispersion of NMR signals, allowing the assignment of nearly all the NOE signals of a selected hexamer in aqueous solution. The NOEs between protons on nonadjacent residues are characteristic of the 12-helix. 3-Substituted ACPC residues allow one to arrange specific functional groups in a geometrically defined fashion, which should facilitate the design of beta-peptides for biological applications. 相似文献
9.
Oligomers of β‐substituted β‐amino acids (‘β3‐peptides') are known to adopt a helical secondary structure defined by 14‐membered ring hydrogen bonds ('14‐helix'). Here, we describe a deca‐β3‐peptide, 1 , that does not adopt the 14‐helical conformation and that may prefer an alternative secondary structure. β3‐Peptide 1 is composed exclusively of residues with side chains that are not branched adjacent to the β‐C‐atom (β3‐hLeu, β3‐hLys, and β3‐hTyr). In contrast, an analogous β‐peptide, 2 , containing β3‐hVal residues in place of the β3‐hLeu residues of 1 , adopts a 14‐helical conformation in MeOH, according to CD data. These results illustrate the importance of side‐chain branching in determining the conformational preferences of β3‐peptides. 相似文献
10.
Prof. Pil Seok Chae Andrew C. Kruse Dr. Kamil Gotfryd Rohini R. Rana Kyung Ho Cho Prof. Søren G. F. Rasmussen Hyoung Eun Bae Richa Chandra Prof. Ulrik Gether Prof. Lan Guan Prof. Brian K. Kobilka Prof. Claus J. Loland Dr. Bernadette Byrne Prof. Samuel H. Gellman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(46):15645-15651
Integral membrane proteins play central roles in controlling the flow of information and molecules across membranes. Our understanding of membrane protein structures and functions, however, is seriously limited, mainly due to difficulties in handling and analysing these proteins in aqueous solution. The use of a detergent or other amphipathic agents is required to overcome the intrinsic incompatibility between the large lipophilic surfaces displayed by the membrane proteins in their native forms and the polar solvent molecules. Here, we introduce new tripod amphiphiles displaying favourable behaviours toward several membrane protein systems, leading to an enhanced protein solubilisation and stabilisation compared to both conventional detergents and previously described tripod amphiphiles. 相似文献