Showing papers on "Hydrogen bond published in 1987"
1,051 citations
TL;DR: The tendency of certain lipids to self-associate, their asymmetric distribution in SUVs, their preferential association with cholesterol in non-cocrystallizing mixtures, their temperature-induced transitions to the hexagonal phase and their inhibitory effect on penetration of hydrophobic residues of proteins partway into the bilayer can all be explained by their participation in intermolecular hydrogen bonding interactions.
723 citations
TL;DR: The crystal structures of d(CGCA3T3GCG) complex to the antitumor drug distamycin and the DNA fragment alone were solved by x-ray diffraction at 2.2 and 2.5 A resolution, respectively, suggesting a model to explain the unusual properties of poly-(dA).poly(dT) in which a modified B conformation is associated with a large propeller twist of the bases and a set of continuous bifurcating hydrogen bonds
Abstract: The crystal structures of d(CGCA3T3GCG) complex to the antitumor drug distamycin and the DNA fragment alone were solved by x-ray diffraction at 2.2 and 2.5 A resolution, respectively. The drug lies in the narrow minor groove near the center of the B-DNA fragment covering 5 of the 6 A.T base pairs. It is bound to the DNA by hydrogen bonding, van der Waals, and electrostatic interactions. In addition, the DNA was found to have an unusual conformation in the (dA)3.(dT)3 regions. These base pairs have a high positive propeller twist so that in the major groove the adenine amino group is located intermediate between the carbonyl O-4 groups of two adjacent thymines of the opposite strand, making bifurcated hydrogen bonds to the two thymine residues. This suggests a model to explain the unusual properties of poly-(dA).poly(dT) in which a modified B conformation is associated with a large propeller twist of the bases and a set of continuous bifurcating hydrogen bonds along the major groove, which may provide incremental stability to these segments. In addition, shorter segments of (dA)3-6.(dT)3-6 may have this conformation in the midst of B-DNA and stabilize bends in the DNA that may be associated with stacking on one of the high propeller-twisted bases at the ends of these segments.
568 citations
TL;DR: The strength of macroscopic adhesive bonds of polymers is directly proportional to the microscopic exothermic interfacial energy changes of bond formation, as measured by Dupre's 'work of adhesion'.
Abstract: The strength of macroscopic adhesive bonds of polymers is known to be directly proportional to the microscopic exothermic interfacial energy changes of bond formation, as measured by Dupre's 'work of adhesion'. Since the work of adhesion can be very appreciably increased by interfacial acid-base bonding with concomitant increases in adhesive bond strength, it is important to understand the acid-base character of polymers and of the surface sites of substrates or of the reinforcing fillers of polymer composites. The best known acid-base bonds are the hydrogen bonds; these are typical of acid-base bonds, with interaction energies dependent on the acidity of the hydrogen donor and on the basicity of the hydrogen acceptor. The strengths of the acidic or basic sites of polymers and of inorganic substrates can be easily determined by spectroscopic or calorimetric methods, and from this information one can start to predict the strengths of adhesive bonds. An important application of the new knowledge of interfac...
521 citations
TL;DR: In this paper, the photochromic and thermochromic properties of salicylaldehydes with anilines, aminopyridines or benzylamines were investigated in the crystalline state and in rigid glasses at various temperatures.
499 citations
TL;DR: The hydrogen bond is a ubiquitous element of molecular recognition as mentioned in this paper, and it has been shown that an individual uncharged hydrogen bond contributes some 0.5 to 1.8 kcal mol −1 to binding energy and a factor of two to twenty to specificity.
422 citations
TL;DR: Refinement has confirmed that the copper co-ordination is best described as distorted trigonal planar, with strong in-plane bonds to His46 NDelta 1, His117 N delta 1 and Cys112 S gamma, and much weaker axial interactions with Met121 S delta and Gly45 C = O.
343 citations
TL;DR: The structure of poplar plastocyanin in the reduced (CuI) state has been determined and refined, using counter data recorded from crystals at pH 3.8 and 7.8, and the trigonal geometry of the Cu atom strongly favours CuI, so that this form of the protein should be redox-inactive.
304 citations
271 citations
269 citations
01 Jan 1987
TL;DR: Hydration Water and Hydrogen Bonds: Experimental Difficulties, Cooperativity, and Three-Center Bonds and Cooperativity in Cyclic Mot!fs Formed by O-H Groups.
Abstract: PERSPECTIVES aND OVERVIEW 93 Hydration Water and Hydrogen Bonds: Experimental Difficulties, Cooperativity, and Three-Center Bonds 94 CYCLODEXTRIN HYDRATES AS MODEL SYSTEMS FOR THE STUDY OF HYDROGEN BONDING .. 96 Cooperativity in Cyclic Mot!fs Formed by O-H Groups 97 Cooperativity of Hydrogen Bonding Flip-Flop Dynamics 98
TL;DR: From these results and the crystallographic analysis in the next report, it can be inferred that the value of 4.0 kilocalories per mole represents the intrinsic binding energy arising from a highly specific hydrogen binding interaction.
Abstract: This and two accompanying reports describe the intrinsic binding energy derived from a single hydrogen bond between an inhibitor and an enzyme. The results were obtained by comparing matched pairs of inhibitors of the zinc endopeptidase thermolysin that bind to the enzyme in an essentially identical manner but differ in the presence or absence of a specific hydrogen bond. This report describes five phosphorus-containing analogs of the peptides carbobenzoxy-Gly-Leu-X, in which the Gly-Leu peptide linkage is replaced with a phosphonate ester (-PO2(-)-O-). Values for the inhibition constants of these inhibitors show a direct relation with those of the corresponding phosphonamidate analogs (-PO2(-)-NH- in place of the Gly-Leu peptide moiety), which have been characterized previously as transition state analogs. However, each phosphonate ester is bound about 840 times more weakly than the analogous phosphonamidate, reflecting the loss of 4.0 +/- 0.1 kilocalories per mole in binding energy. From these results and the crystallographic analysis in the next report, it can be inferred that the value of 4.0 kilocalories per mole represents the intrinsic binding energy arising from a highly specific hydrogen binding interaction.
TL;DR: It is found that the steric hindrance of ligand binding by the E11 residue and the polarity of the E7 residue in the β subunit are critical for fine-tuning ligand affinity.
Abstract: The geometries of the Fe–O2 and Fe–CO bonds in myoglobin and haemoglobin differ significantly from those in free porphyrin model compounds1–6. It has been suggested that steric hindrance by Val-Ell and His-E7 and a hydrogen bond between His-E7 and oxygen2,4,7 affect the geometry and electronic state of the Fe-ligand bond, and that these interactions may be important in controlling oxygen affinity8. We have produced mutant haemoglobins in E. coli9–11 having Val(67β)E11 replaced by Ala, Met, Leu or Ile and His(58β)E7 by Gin, Val or Gly. We have studied the effect of these mutations on the equilibrium and kinetics of ligand binding. The conformation of the new side chains and their effect on the protein structure have been examined by X-ray crystallography, and the vibrational properties of the Fe–CO bond observed by resonance Raman spectroscopy12. We found that the steric hindrance of ligand binding by the E11 residue and the polarity of the E7 residue in the β subunit are critical for fine-tuning ligand affinity.
TL;DR: Etudes spectrometriques UV visible, RMN 1 H et effet Overhauser de melanges de propylamide de N-(dinitro-3,5 benzoyl) leucine et de naphtyl-2 alaninate de methyle
Abstract: Etudes spectrometriques UV visible, RMN 1 H et effet Overhauser de melanges de propylamide de N-(dinitro-3,5 benzoyl) leucine et de N-(naphtyl-2) alaninate de methyle
TL;DR: A critical evaluation of the work that has been done to gather evidence, as well as of earlier work involving condensed-phase observations, suggests that NH3 might well be best described as a powerful hydrogen-bond acceptor with little propensity to donate hydrogen bonds.
Abstract: Spectroscopic characterizations of the stereochemistry of complexes of ammonia (NH(3)) have strongly confirmed some long-held ideas about the weak interactions of NH(3) while casting doubt on others. As expected, NH(3) is observed to be a nearly universal proton acceptor, accepting hydrogen bonds from even some of the weakest proton donors. Surprisingly, no evidence has been found to support the view that NH(3) acts as a proton donor through hydrogen bonding. A critical evaluation of the work that has been done to gather such evidence, as well as of earlier work involving condensed-phase observations, suggests that NH(3) might well be best described as a powerful hydrogen-bond acceptor with little propensity to donate hydrogen bonds.
TL;DR: In this article, thermal parameters for duplex formation by self-complementary oligomers ICCGGC, CGGCCI, ICCGG, and GGCCI are reported.
Abstract: Thermodynamic parameters for duplex formation by self-complementary oligomers ICCGGC, CGGCCI, ICCGG, and GGCCI are reported.
TL;DR: The mode of binding to thermolysin of the ester analog Cbz-GlyP-(O)-Leu-Leu has been determined by x-ray crystallography and shown to be virtually identical with the corresponding peptide analog CnP-(NH)-Lei-Lei.
Abstract: The mode of binding to thermolysin of the ester analog Cbz-GlyP-(O)-Leu-Leu has been determined by x-ray crystallography and shown to be virtually identical (maximum difference 0.2 angstrom) with the corresponding peptide analog Cbz-GlyP-(NH)-Leu-Leu. The two inhibitors provide a matched pair of enzyme-inhibitor complexes that differ by 4.1 kilocalories per mole in intrinsic binding energy but are essentially identical except for the presence or absence of a specific hydrogen bond.
TL;DR: The enol structure of gaseous acetylacetone has been determined from electron diffraction data as mentioned in this paper, and the molecular skeleton is planar but it is not symmetric.
TL;DR: The structure of the complex formed between alpha-lytic protease, a serine protease secreted by Lysobacter enzymogenes, and N-tert-butyloxycarbonylalanylprolylvaline boronic acid has been studied by X-ray crystallography and it is suggested that in its native state the enzyme is complementary to tetrahedral reaction intermediates or to the nearly Tetrahedral transition state for the reaction.
Abstract: The structure of the complex formed between alpha-lytic protease, a serine protease secreted by Lysobacter enzymogenes, and N-tert-butyloxycarbonylalanylprolylvaline boronic acid (Ki = 0.35 nM) has been studied by X-ray crystallography to a resolution of 2.0 A. The active-site serine forms a covalent, nearly tetrahedral adduct with the boronic acid moiety of the inhibitor. The complex is stabilized by seven hydrogen bonds between the enzyme and inhibitor with additional stabilization arising from van der Waals interactions between enzyme and inhibitor side chains and the burying of 330 A2 of hydrophobic surface area. Hydrogen bonding between Asp-102 and His-57 remains intact in the enzyme-inhibitor complex, and His N epsilon 2 is well positioned to donate its hydrogen to the leaving group. Little change in the positions of protease residues was observed on complex formation (root mean square main chain deviation = 0.13 A), suggesting that in its native state the enzyme is complementary to tetrahedral reaction intermediates or to the nearly tetrahedral transition state for the reaction.
TL;DR: The crystal structure of a deletion mutant of tyrosyl-tRNA synthetase from Bacillus stearothermophilus has been determined at 2.5 A resolution using molecular replacement techniques.
TL;DR: Since there is only one peptide molecule per cell in space group P1, the molecules repeat only by translation, and consequently the helices pack parallel to each other.
Abstract: Boc-Trp-Ile-Ala-Aib-Ile-Val-Aib-Leu-Aib-Pro-Ala-Aib-Pro-Aib-Pro-Phe-OMe (where Boc is t-butoxycarbonyl and Aib is alpha-aminoisobutyric acid), a synthetic apolar analog of the membrane-active fungal peptide antibiotic zervamycin IIA, crystallizes in space group P1 with Z = 1 and cell parameters a = 9.086 +/- 0.002 A, b = 10.410 +/- 0.002 A, c = 28.188 +/- 0.004 A, alpha = 86.13 +/- 0.01 degrees, beta = 87.90 +/- 0.01 degrees, and gamma = 89.27 +/- 0.01 degrees; overall agreement factor R = 7.3% for 7180 data (F0 greater than 3 sigma) and 0.91-A resolution. The peptide backbone makes a continuous spiral that begins as a 3(10)-helix at the N-terminus, changes to an alpha-helix for two turns, and ends in a spiral of three beta-bends in a ribbon. Each of the beta-bends contains a proline residue at one of the corners. The torsion angles phi i range from -51 degrees to -91 degrees (average value -64 degrees), and the torsion angles psi i range from -1 degree to -46 degrees (average value -31 degrees). There are 10 intramolecular NH...OC hydrogen bonds in the helix and two direct head-to-tail hydrogen bonds between successive molecules. Two H2O and two CH3OH solvent molecules fill additional space with appropriate hydrogen bonding in the head-to-tail region, and two additional H2O molecules form hydrogen bonds with carbonyl oxygens near the curve in the helix at Pro-10. Since there is only one peptide molecule per cell in space group P1, the molecules repeat only by translation, and consequently the helices pack parallel to each other.
TL;DR: In this article, the adsorption of water on clean and oxygen covered Ag(110) in ultrahigh vacuum was studied with thermal desorption spectroscopy (TDS), electron stimulated Desorption ion angular distribution (ESDIAD), low energy electron diffraction (LEED), work function measurements (Δ), and Auger electron spectroscopic (AES).
TL;DR: In this article, the structure of crystalline α-cyclodextrin (α-CD) hexahydrate, form I (C36H60O30·6H2O, space group P212121) is experimentally so well determined by X-ray and by neutron diffraction analyses that the positions of all the hydrogen atoms are available.
Abstract: The structure of crystalline α-cyclodextrin (α-CD) hexahydrate, form I (C36H60O30·6H2O, space group P212121) is experimentally so well determined by X-ray and by neutron diffraction analyses that the positions of all the hydrogen atoms are available. This provides an opportunity for testing an empirical force field that is currently used in simulations of protein and nucleic acid structures by performing molecular dynamics studies employing the GROMOS program package on a system of 4 unit cells containing 16 α-CD molecules and 96 water molecules.
TL;DR: In this article, the authors used dilute aqueous solutions of the extracellular polysaccharides from Pseudomonas elodea (S-60), Alcaligenes (ATCC 31555), S-130, and Alcaligens (atCC 31961), and S-194 over a range of ionic strength (Me4NCl concentrations) and temperature.
Patent•
3M1
TL;DR: In this paper, an electricallyconductive, pressure-sensitive adhesive composition having a polymeric matrix comprised of copolymers of hydrogen bond donating monomer (for example acrylic acid) and hydrogen bond accepting monomers (for instance N-vinylpyrrolidone) is disclosed.
Abstract: An electrically-conductive, pressure-sensitive adhesive composition having a polymeric matrix comprised of copolymers of hydrogen bond donating monomer (for example acrylic acid) and hydrogen bond accepting monomers (for example N-vinylpyrrolidone) is disclosed. The polymeric matrix is homogeneously mixed with an electrically-conductive plasticizing solution comprised of from 0% to 98% by weight water-soluble, polar organic compound (for example glycerol), 2% to 100% by weight water, and 0 to 12% by weight water-soluble salt. The composition contains from about 12% to 50% by weight non-volatile copolymer matrix and the hydrogen bond donating sites on the copolymer matrix are froma bout 5% to about 95% neutralized. Free radical polymerization methods of making the composition and biomedical electrodes incorporating the composition are also described.
TL;DR: The conservation, during evolution, of a ring of acidic residues in the proximity of the FeSG4 center suggests that this ring may be implicated in the recognition processes between rubredoxins and their functional partners.