Introduction History Definition Types of H bond Hydrogen bond in water Bifurcated and over - Coordinated hydrogen bond in water Hydrogen bonds in DNA and proteins Hydrogen bonds in polymers Systematic hydrogen bond Importance of hydrogen bond Conclusion References

1. HYDROGEN BOND
By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )

2. SYNOPSIS
• Introduction
• History
• Definition
• Types of H bond
• Hydrogen bond in water
• Bifurcated and over - Coordinated hydrogen bond in water
• Hydrogen bonds in DNA and proteins
• Hydrogen bonds in polymers
• Systematic hydrogen bond
• Importance of hydrogen bond
• Conclusion
• References

3. Introduction
• When a hydrogen atom is covalently bonded to an
electronegative atom, particularly an oxygen or a
nitrogen atom, the single pair of shared electrons is
greatly displaced toward the nucleus of the
electronegative atom, leaving the hydrogen atom with a
partial positive charge.
fig: hydrogen bond

4. History
• The nature of the chemical bond, Linus Pauling
credits T. S. Moore and T. F. Winmill with the first
mention of the hydrogen bond, in 1912.

5. Definition
• A hydrogen bond is the attractive force between the
hydrogen attached to an electronegative atom of one
molecule and an electronegative atom of a different
molecule.
fig:hydrogen bond

6. Types of hydrogen bond
These are two types –
1. Intramolecular hydrogen bond - Some compound,
Hydrogen bond can be formed within molecules.
These are called intramolecular hydrogen bond.
Example:
ortho hydroxy benzildehyde
2. Intermolecular hydrogen bond – When hydrogen
bond is formed in two different molecules is called
intramolecular hydrogen bond.
Example: H2O

7. Hydrogen bonds in water
• Water molecules rarely ionize to form H+ and OH-
ion. Instead, they exist as polar H-O-H molecules with
both the hydrogen and oxygen atoms can bind to
external H atom, whereas each H atom can bind to
one adjacent oxygen
atom.
fig:hydrogen bond in water

8. Bifurcated over - Coordinated hydrogen
bond in water
• It can be that a single hydrogen atom participates in
two hydrogen bonds, rather than one. This type of
bonding is called "bifurcated“.
• It was suggested that a bifurcated hydrogen atom is
an essential step in water reorientation.

9. Hydrogen bonds in DNA and proteins
• The double helical structure of DNA is due largely to
hydrogen bonding between its base pairs, which link
one complementary strand to the other and enable
replications.
• In the secondary structure of proteins, hydrogen
bonds form between the backbone oxygens and
amide hydrogens.

10. Hydrogen bond in polymers
• The synthetic polymers, where hydrogen bonds occur
in the repeat unit and play a major role in
crystallization of the material.
• The bonds occur between carbonyl and amine groups
in the amide repeat unit.(nylon)

11. Symmetric hydrogen bond
• A symmetric hydrogen bond is a special type of
hydrogen bond in which the proton is spaced exactly
halfway between two identical atoms.
• This type of bond is much stronger than a "normal"
hydrogen bond.

12. Importance of hydrogen bond
• H bonds are individually weak but collectively
they have a very significant influence on the these
dimensional structures of protein, nucleic acid,
polysaccherides and membrane lipids.
• H bonds stabilize proteins and nucleic acids.

13. Conclusion
• Hydrogen bond play a very important role in folding
of protein or any molecule. Thus, determining their
function.
• Any compound is soluble in water due to hydrogen
bonding.

14. References
• Gerald Karp – cell and molecular biology 6th Edition
• Watson - Molecular biology of the gene 5th Edition
• http://en.wikipedia.org (7:30pm 23aug)
• http://www.ncbi.nlm.nih.gov (7:15pm 23aug)