scholarly journals Modulation of the Axial Water Hydrogen-Bonding Properties by Chemical Modification of the Substrate in Resting State, Substrate-Bound Heme Oxygenase fromNeisseria meningitidis; Coupling to the Distal H-Bond Network via Ordered Water Molecules

2006 ◽  
Vol 128 (19) ◽  
pp. 6391-6399 ◽  
Author(s):  
Li-Hua Ma ◽  
Yangzhong Liu ◽  
Xuhong Zhang ◽  
Tadashi Yoshida ◽  
Kevin C. Langry ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Modification ◽  
Heme Oxygenase ◽  
Resting State ◽  
Water Molecules ◽  
Bonding Properties ◽  
Bond Network ◽  
Ordered Water ◽  
Water Hydrogen

scholarly journals Origin of hydrophobicity and enhanced water hydrogen bond strength near purely hydrophobic solutes

2016 ◽  
Vol 114 (2) ◽  
pp. 322-327 ◽  
Author(s):  
Joze Grdadolnik ◽  
Franci Merzel ◽  
Franc Avbelj
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Hydrophobic Hydration ◽  
Bulk Water ◽  
Water Molecules ◽  
Classical View ◽  
Fundamental Level ◽  
Hydrophobic Solute ◽  
Hydrophobic Solutes ◽  
Water Hydrogen

Hydrophobicity plays an important role in numerous physicochemical processes from the process of dissolution in water to protein folding, but its origin at the fundamental level is still unclear. The classical view of hydrophobic hydration is that, in the presence of a hydrophobic solute, water forms transient microscopic “icebergs” arising from strengthened water hydrogen bonding, but there is no experimental evidence for enhanced hydrogen bonding and/or icebergs in such solutions. Here, we have used the redshifts and line shapes of the isotopically decoupled IR oxygen–deuterium (O-D) stretching mode of HDO water near small purely hydrophobic solutes (methane, ethane, krypton, and xenon) to study hydrophobicity at the most fundamental level. We present unequivocal and model-free experimental proof for the presence of strengthened water hydrogen bonds near four hydrophobic solutes, matching those in ice and clathrates. The water molecules involved in the enhanced hydrogen bonds display extensive structural ordering resembling that in clathrates. The number of ice-like hydrogen bonds is 10–15 per methane molecule. Ab initio molecular dynamics simulations have confirmed that water molecules in the vicinity of methane form stronger, more numerous, and more tetrahedrally oriented hydrogen bonds than those in bulk water and that their mobility is restricted. We show the absence of intercalating water molecules that cause the electrostatic screening (shielding) of hydrogen bonds in bulk water as the critical element for the enhanced hydrogen bonding around a hydrophobic solute. Our results confirm the classical view of hydrophobic hydration.

scholarly journals Unusual Properties of Water

2012 ◽  
Vol 7 (1) ◽  
pp. 20-23
Author(s):  
Janusz Lipkowski
Keyword(s):  
Hydrogen Bonding ◽  
Cold Water ◽  
Hot Water ◽  
Water Molecules ◽  
Condensed Phases ◽  
Cohesion Energy ◽  
Web Page ◽  
Structures And Properties ◽  
Structural Aspects ◽  
Water Hydrogen

Water has been known for its unusual properties from antiquity when, e.g. was found that hot water freezes faster than cold water. Presently, on the web page 'water' Martin Chaplin [1] lists sixty seven properties of water which may be considered 'anomalous' when comparing to 'normal' chemical substances. Much of this can be attributed to the spatial structure of hydrogen bonding in condensed phases of water. Hydrogen bonding constitutes about 2/3 of cohesion energy of water. However, the remaining 1/3 is definitely not negligible. Combination of the two leads to properties of water in the systems where it plays a role. The very comprehensive range of such systems and common presence of water make the enormous variety of structures and properties of water-containing compounds. In the present paper the non-hydrophilic component of properties of water will be emphasized in combination with the structural aspects of supramolecular bonding of water molecules.

L-Leucylglycine 0.67-hydrate and [(4S)-2,2-dimethyl-4-(2-methylpropyl)-5-oxoimidazolidin-3-ium-1-yl]acetate

2012 ◽  
Vol 68 (12) ◽  
pp. o498-o501 ◽  
Author(s):  
Tamiko Kiyotani ◽  
Yoko Sugawara
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Carbonyl Group ◽  
Water Molecules ◽  
Hydrogen Bond Network ◽  
Amino Groups ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Bond Network

Crystals of L-leucylglycine (L-Leu–Gly) 0.67-hydrate, C8H16N2O3·0.67H2O, (I), were obtained from an aqueous solution. There are three symmetrically independent dipeptide zwitterionic molecules in (I) and they are parallel to one another. The hydrogen-bond network composed of carboxylate and amino groups and water molecules extends parallel to theabplane. Hydrophilic regions composed of main chains and hydrophobic regions composed of the isobutyl groups of the leucyl residues are aligned alternately along thecaxis. An imidazolidinone derivative was obtained from L-Leu–Gly and acetone,viz.[(4S)-2,2-dimethyl-4-(2-methylpropyl)-5-oxoimidazolidin-3-ium-1-yl]acetate, C11H20N2O3, (II), and was crystallized from a methanol–acetone solution of L-Leu–Gly. The unit-cell parameters coincide with those reported previously for L-Leu–Gly dihydrate revealing that the previously reported values should be assigned to the structure of (II). One of the imidazolidine N atoms is protonated and the ring is nearly planar, except for the protonated N atom. Protonated N atoms and deprotonated carboxy groups of neighbouring molecules form hydrogen-bonded chains. The ring carbonyl group is not involved in hydrogen bonding.

scholarly journals Coupling of the Distal Hydrogen Bond Network to the Exogenous Ligand in Substrate-Bound, Resting State Human Heme Oxygenase

Biochemistry ◽  
2009 ◽  
Vol 48 (47) ◽  
pp. 11231-11242 ◽  
Author(s):  
Dungeng Peng ◽  
Hiroshi Ogura ◽  
Wenfeng Zhu ◽  
Li-Hua Ma ◽  
John P. Evans ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Heme Oxygenase ◽  
Resting State ◽  
Hydrogen Bond Network ◽  
Bond Network ◽  
Exogenous Ligand

1H NMR Detection of Immobilized Water Molecules within a Strong Distal Hydrogen-Bonding Network of Substrate-Bound Human Heme Oxygenase-1

2002 ◽  
Vol 124 (48) ◽  
pp. 14296-14297 ◽  
Author(s):  
Ray T. Syvitski ◽  
Yiming Li ◽  
Karine Auclair ◽  
Paul R. Ortiz de Montellano ◽  
Gerd N. La Mar
Keyword(s):  
Hydrogen Bonding ◽  
1H Nmr ◽  
Heme Oxygenase ◽  
Heme Oxygenase 1 ◽  
Water Molecules ◽  
Hydrogen Bonding Network

Utilization of electrical charges in the pores of tofu waste for hydrogen production in water

2020 ◽  
pp. 124-135
Author(s):  
I. N. G. Wardana ◽  
N. Willy Satrio
Keyword(s):  
Magnetic Field ◽  
Hydrogen Production ◽  
Sodium Bicarbonate ◽  
Positive Charge ◽  
Electrical Energy ◽  
Hydrogen Sensor ◽  
Water Molecules ◽  
Partial Charge ◽  
Delocalized Electron ◽  
Water Hydrogen

Tofu is main food in Indonesia and its waste generally pollutes the waters. This study aims to change the waste into energy by utilizing the electric charge in the pores of tofu waste to produce hydrogen in water. The tofu pore is negatively charged and the surface surrounding the pore has a positive charge. The positive and negative electric charges stretch water molecules that have a partial charge. With the addition of a 12V electrical energy during electrolysis, water breaks down into hydrogen. The test was conducted on pre-treated tofu waste suspension using oxalic acid. The hydrogen concentration was measured by a MQ-8 hydrogen sensor. The result shows that the addition of turmeric together with sodium bicarbonate to tofu waste in water, hydrogen production increased more than four times. This is due to the fact that magnetic field generated by delocalized electron in aromatic ring in turmeric energizes all electrons in the pores of tofu waste, in the sodium bicarbonate, and in water that boosts hydrogen production. At the same time the stronger partial charge in natrium bicarbonate shields the hydrogen proton from strong attraction of tofu pores. These two combined effect are very powerful for larger hydrogen production in water by tofu waste.

PEMANFAATAN GLISERIN DARI RESIDU GLISERIN SEBAGAI PLASTICIZER UNTUK PEMBUATAN BIOPLASTIK DENGAN BAHAN BAKU PATI BONGGOL PISANG KEPOK

2017 ◽  
Vol 5 (4) ◽  
pp. 26-32 ◽  
Author(s):  
Azaria Robiana ◽  
M. Yashin Nahar ◽  
Hamidah Harahap
Keyword(s):  
Tensile Strength ◽  
Hydrogen Bonding ◽  
Fatty Acid ◽  
Maximum Yield ◽  
Sem Analysis ◽  
Water Molecules ◽  
Banana Weevil ◽  
Gelatinization Temperature ◽  
Recharge Area ◽  
Maximum Quantity

Glycerin residue is waste oleochemical industry that still contain glycerin. To produce quality and maximum quantity of glycerin, then research the effect of pH acidification using phosphoric acid. Glycerin analysis includes the analysis of pH, Fatty Acid and Ester (FAE), and analysis of the levels of glycerin. The maximum yield obtained at pH acidification 2 is grading 91,60% glycerin and Fatty Acid and Ester (FAE) 3,63 meq/100 g. Glycerin obtained is used as a plasticizer in the manufacture of bioplastics. Manufacture of bioplastics using the method of pouring a solution with varying concentrations of starch banana weevil (5% w/v and 7% w/v), variations of the addition of glycerin (1 ml, 3 ml, 5 ml and 7 ml), and a variety of gelatinization temperature (60°C, 70°C, and 80°C). Analysis of bioplastics include FTIR testing, tensile strength that is supported by SEM analysis. The results obtained in the analysis of FTIR does not form a new cluster on bioplastics starch banana weevil, but only a shift in the recharge area only, it is due to the addition of O-H groups originating from water molecules that enter the polysaccharide through a mechanism gelatinitation that generates interaction hydrogen bonding strengthened. The maximum tensile strength of bioplastics produced at a concentration of starch 7% w/v, 1 ml glycerine and gelatinization temperature of 80°C is 3,430 MPa. While the tensile strength bioplastic decreased with increasing glycerin which can be shown from the results of SEM where there is a crack, indentations and lumps of starch insoluble.

Study on the effect of protein buffer solution on hydrogen bonding of water molecules based on terahertz metamaterial absorber

Optik ◽  
2021 ◽  
Vol 238 ◽  
pp. 166771
Author(s):  
Jianjun Liu ◽  
Tiejun Li ◽  
Senquan Yan ◽  
Haoxiang Wen ◽  
Fan Ding
Keyword(s):  
Hydrogen Bonding ◽  
Metamaterial Absorber ◽  
Water Molecules ◽  
Buffer Solution
Sign in / Sign up

Export Citation Format

Share Document