Hydrogen bonds

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A [[Hydrogen|hydrogen]] bond is an attraction between a [[Hydrogen|hydrogen]] atom and an [[Electronegative|electronegative]]&nbsp;atom, most common ones being&nbsp;[[Nitrogen|nitrogen]]&nbsp;(N), [[Oxygen|oxygen]]&nbsp;(O) or [[Fluorine|fluorine]]&nbsp;(F). Hydrogen bonds appear frequently within biological molecules and it exists in [[Compound|polar compounds]], a common example of&nbsp;this being&nbsp;[[Water|water]] where the attractive&nbsp;nteraction exists between the [[Oxygen|oxygen]] and [[Hydrogen|hydrogen]]. [[Hydrogen|Hydrogen]] bonding&nbsp;occurs as [[Intermolecular|intermolecular]] attractions, where the Hydrogen bond&nbsp;is found&nbsp;between different [[Molecule|molecules]], or [[Intramolecular|intramolecular]], where the bond exists between different parts of the same [[Molecule|molecule]]&nbsp;<ref>http://www.chemguide.co.uk/atoms/bonding/hbond.html</ref>.  
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A [[Hydrogen|hydrogen]] bond is an attraction between a [[Hydrogen|hydrogen]] atom and an [[Electronegative|electronegative]]&nbsp;atom, most common ones being&nbsp;[[Nitrogen|nitrogen]]&nbsp;(N), [[Oxygen|oxygen]]&nbsp;(O) or [[Fluorine|fluorine]]&nbsp;(F). Hydrogen bonds appear frequently within biological molecules and it exists in [[Compound|polar compounds]], a common example of&nbsp;this being&nbsp;[[Water|water]] where the attractive interaction exists between the [[Oxygen|oxygen]] and [[Hydrogen|hydrogen]]. [[Hydrogen|Hydrogen]] bonding&nbsp;occurs as [[Intermolecular|intermolecular]] attractions, where the Hydrogen bond&nbsp;is found&nbsp;between different [[Molecule|molecules]], or [[Intramolecular|intramolecular]], where the bond exists between different parts of the same [[Molecule|molecule]]&nbsp;<ref>http://www.chemguide.co.uk/atoms/bonding/hbond.html</ref>.  
  
 
A [[Hydrogen|hydrogen]] bond is a non-covalent bond; they&nbsp;have&nbsp;much&nbsp;stronger attractions than [[Van der waals forces|Van der Waals&nbsp;forces]] and [[Permanent dipole - permanent dipole interactions|permanent dipole-permanent dipole interactions]], but are weaker than [[Ionic bonding|ionic bonding or]] [[Covalent bonding|covalent bonding]]. Evidence for [[Hydrogen|hydrogen]] bonding can be found when comparing the [[Boiling point|boiling points]] of [[Hydrogen|hydrogen]] molecules&nbsp;across groups 5, 6 and 7 of the [[Periodic table|periodic table]]. The compounds where [[Hydrogen|hydrogen]] bonding is present produce a much higher [[Boiling point|boiling point]] as [[Hydrogen|hydrogen]] bonds require more energy to be broken than [[Van der waals forces|Van der Waals forces]]&nbsp;<ref>http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/HydrogenBonds.html</ref>.  
 
A [[Hydrogen|hydrogen]] bond is a non-covalent bond; they&nbsp;have&nbsp;much&nbsp;stronger attractions than [[Van der waals forces|Van der Waals&nbsp;forces]] and [[Permanent dipole - permanent dipole interactions|permanent dipole-permanent dipole interactions]], but are weaker than [[Ionic bonding|ionic bonding or]] [[Covalent bonding|covalent bonding]]. Evidence for [[Hydrogen|hydrogen]] bonding can be found when comparing the [[Boiling point|boiling points]] of [[Hydrogen|hydrogen]] molecules&nbsp;across groups 5, 6 and 7 of the [[Periodic table|periodic table]]. The compounds where [[Hydrogen|hydrogen]] bonding is present produce a much higher [[Boiling point|boiling point]] as [[Hydrogen|hydrogen]] bonds require more energy to be broken than [[Van der waals forces|Van der Waals forces]]&nbsp;<ref>http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/HydrogenBonds.html</ref>.  
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The distance between two parts of the same&nbsp;[[Molecule|molecule]], or different [[Molecule|molecule]], can vary and this has an effect on the strength of the hydrogen&nbsp;bond. This why the hydrogen bonds are said to be "elastic," the greater the distance between the [[Hydrogen|hydrogen]] [[Atom|atom]] and the electronegative atom the longer the hydrogen bond will be and this results in&nbsp;a weaker hydrogen bond.  
 
The distance between two parts of the same&nbsp;[[Molecule|molecule]], or different [[Molecule|molecule]], can vary and this has an effect on the strength of the hydrogen&nbsp;bond. This why the hydrogen bonds are said to be "elastic," the greater the distance between the [[Hydrogen|hydrogen]] [[Atom|atom]] and the electronegative atom the longer the hydrogen bond will be and this results in&nbsp;a weaker hydrogen bond.  
  
A hydrogen bond can be defined as the polar&nbsp;interaction&nbsp;between an electronegative atom ([[Nitrogen]], [[Oxygen|oxygen]] or [[fluorine|fluorine]]) and a hydrogen atom&nbsp;which is&nbsp;covalently&nbsp;bonded to&nbsp;another electronegative atom that is wither on the same molecule, or on a different molecule. The bond is strongest when all three of these atoms are arranged in a way in which they can be linked along a straight line&nbsp;<ref>Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p57.</ref>.
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A hydrogen bond can be defined as the polar&nbsp;interaction&nbsp;between an electronegative atom ([[Nitrogen]], [[Oxygen|oxygen]] or [[Fluorine|fluorine]]) and a hydrogen atom&nbsp;which is&nbsp;covalently&nbsp;bonded to&nbsp;another electronegative atom that is wither on the same molecule, or on a different molecule. The bond is strongest when all three of these atoms are arranged in a way in which they can be linked along a straight line&nbsp;<ref>Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p57.</ref>.  
  
Hydrogen bonding is&nbsp;extremely prevalent throughout nature and can be found in [[Water|water]], [[DNA|DNA]] base-pair interactions, protein folding, [[protein|protein]] structure and protein-ligand binding.  
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Hydrogen bonding is&nbsp;extremely prevalent throughout nature and can be found in [[Water|water]], [[DNA|DNA]] base-pair interactions, protein folding, [[Protein|protein]] structure and protein-ligand binding.  
  
 
=== Water  ===
 
=== Water  ===
  
A water molecule consists of one oxygen atom attached to two [[hydrogen|hydrogen]] [[atom|atoms]]. A hydrogen bond can be formed between two [[molecules|molecules]] of [[water|water]] due to the 'unequal distribution of electrons within a water molecule'&nbsp;<ref>Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p55</ref>.&nbsp;The oxygen has a strong attraction for the electrons and has a negative charge, whereas the hydrogen only has a weak attraction and therefore has a slight positive charge. When these two oppositely-charged regions come close to each other, the result is a hydrogen bond&nbsp;<ref>Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p55</ref>.
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A water molecule consists of one oxygen atom attached to two [[Hydrogen|hydrogen]] [[Atom|atoms]]. A hydrogen bond can be formed between two [[Molecules|molecules]] of [[Water|water]] due to the 'unequal distribution of electrons within a water molecule'&nbsp;<ref>Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p55</ref>.&nbsp;The oxygen has a strong attraction for the electrons and has a negative charge, whereas the hydrogen only has a weak attraction and therefore has a slight positive charge. When these two oppositely-charged regions come close to each other, the result is a hydrogen bond&nbsp;<ref>Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p55</ref>.  
  
 
Although water has a low molecular mass, it has an unusually high boiling point. This property can be attributed to the large amount of hydrogen bonds that exists within water. Since these bonds are difficult to break, water’s melting and boiling points are relatively high in comparison to other liquids that are similar but lack the hydrogen bonding.<br>  
 
Although water has a low molecular mass, it has an unusually high boiling point. This property can be attributed to the large amount of hydrogen bonds that exists within water. Since these bonds are difficult to break, water’s melting and boiling points are relatively high in comparison to other liquids that are similar but lack the hydrogen bonding.<br>  
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=== DNA  ===
 
=== DNA  ===
  
In the [[Helix|DNA&nbsp;helix]],the bases: [[adenine|adenine]], [[cytosine|cytosine]], [[thymine|thymine]] and [[guanine|guanine]]&nbsp;are each linked with their complementary base by hydrogen bonding. Adenine pairs with thymine with 2 hydrogen bonds. Guanine pairs with cytosine with 3 hydrogen bonds.<ref>J.M.Berg, J.L.Tymoczko, L.Stryer,(2007) Biochemistry, 6th edition, New York: W.H.Freeman and company p112</ref><br>  
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In the [[Helix|DNA&nbsp;helix]],the bases: [[Adenine|adenine]], [[Cytosine|cytosine]], [[Thymine|thymine]] and [[Guanine|guanine]]&nbsp;are each linked with their complementary base by hydrogen bonding. Adenine pairs with thymine with 2 hydrogen bonds. Guanine pairs with cytosine with 3 hydrogen bonds.<ref>J.M.Berg, J.L.Tymoczko, L.Stryer,(2007) Biochemistry, 6th edition, New York: W.H.Freeman and company p112</ref><br>  
  
 
=== Protein  ===
 
=== Protein  ===
  
An alpha-helix contains hydrogen bonds between the N-H&nbsp;of one peptide bongs and the C=O of another peptide bond which is found 4 [[Peptide_bond|peptide bonds]] away on the same chain.  
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An alpha-helix contains hydrogen bonds between the N-H&nbsp;of one peptide bongs and the C=O of another peptide bond which is found 4 [[Peptide bond|peptide bonds]] away on the same chain.  
  
Also the individual, antiparallel strands of the&nbsp;beta-pleated-sheet&nbsp;have hydrogen bonds which connect the peptide bonds of different strands&nbsp;<ref>Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p137</ref>.<br>
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Also the individual, antiparallel strands of the&nbsp;beta-pleated-sheet&nbsp;have hydrogen bonds which connect the peptide bonds of different strands&nbsp;<ref>Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p137</ref>.<br>  
  
 
=== References:  ===
 
=== References:  ===
  
 
<references /><br>
 
<references /><br>

Revision as of 13:49, 22 November 2012

A hydrogen bond is an attraction between a hydrogen atom and an electronegative atom, most common ones being nitrogen (N), oxygen (O) or fluorine (F). Hydrogen bonds appear frequently within biological molecules and it exists in polar compounds, a common example of this being water where the attractive interaction exists between the oxygen and hydrogen. Hydrogen bonding occurs as intermolecular attractions, where the Hydrogen bond is found between different molecules, or intramolecular, where the bond exists between different parts of the same molecule [1].

A hydrogen bond is a non-covalent bond; they have much stronger attractions than Van der Waals forces and permanent dipole-permanent dipole interactions, but are weaker than ionic bonding or covalent bonding. Evidence for hydrogen bonding can be found when comparing the boiling points of hydrogen molecules across groups 5, 6 and 7 of the periodic table. The compounds where hydrogen bonding is present produce a much higher boiling point as hydrogen bonds require more energy to be broken than Van der Waals forces [2].

The distance between two parts of the same molecule, or different molecule, can vary and this has an effect on the strength of the hydrogen bond. This why the hydrogen bonds are said to be "elastic," the greater the distance between the hydrogen atom and the electronegative atom the longer the hydrogen bond will be and this results in a weaker hydrogen bond.

A hydrogen bond can be defined as the polar interaction between an electronegative atom (Nitrogen, oxygen or fluorine) and a hydrogen atom which is covalently bonded to another electronegative atom that is wither on the same molecule, or on a different molecule. The bond is strongest when all three of these atoms are arranged in a way in which they can be linked along a straight line [3].

Hydrogen bonding is extremely prevalent throughout nature and can be found in water, DNA base-pair interactions, protein folding, protein structure and protein-ligand binding.

Contents

Water

A water molecule consists of one oxygen atom attached to two hydrogen atoms. A hydrogen bond can be formed between two molecules of water due to the 'unequal distribution of electrons within a water molecule' [4]. The oxygen has a strong attraction for the electrons and has a negative charge, whereas the hydrogen only has a weak attraction and therefore has a slight positive charge. When these two oppositely-charged regions come close to each other, the result is a hydrogen bond [5].

Although water has a low molecular mass, it has an unusually high boiling point. This property can be attributed to the large amount of hydrogen bonds that exists within water. Since these bonds are difficult to break, water’s melting and boiling points are relatively high in comparison to other liquids that are similar but lack the hydrogen bonding.

DNA

In the DNA helix,the bases: adenine, cytosine, thymine and guanine are each linked with their complementary base by hydrogen bonding. Adenine pairs with thymine with 2 hydrogen bonds. Guanine pairs with cytosine with 3 hydrogen bonds.[6]

Protein

An alpha-helix contains hydrogen bonds between the N-H of one peptide bongs and the C=O of another peptide bond which is found 4 peptide bonds away on the same chain.

Also the individual, antiparallel strands of the beta-pleated-sheet have hydrogen bonds which connect the peptide bonds of different strands [7].

References:

  1. http://www.chemguide.co.uk/atoms/bonding/hbond.html
  2. http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/HydrogenBonds.html
  3. Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p57.
  4. Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p55
  5. Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p55
  6. J.M.Berg, J.L.Tymoczko, L.Stryer,(2007) Biochemistry, 6th edition, New York: W.H.Freeman and company p112
  7. Alberts, B et al. (2008). Molecular Biology of the Cell. 5th ed. US: Garland Science. 1268. p137

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