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Showing posts from March, 2010

Hydrogen Bonding-I: An overview in Pictures

Hydrogen bonding is one of the most important forces responsible for binding interactions between a drug molecule and a receptor. It is also an important factor which determines the secondary structures of macromolecules like proteins or nucleic acids.
Hydrogen bond (H-bond) is a type of electrostatic bond, significantly weaker than covalent and ionic bonds. H-bond has an energy range of 2.4 to 24 Kcal/mol. Figure 1 shows the H-bond formation between two dipoles. Hydrogen is attached to an electronegative element X. Due to X, the X-H bonding electrons shift towards X resulting in partial negative charge on X and a corresponding partial positive charge on H. H is then attracted by another electronegative element “A” causing the H-bonding between the two dipoles. H-bonding is essential for 3D structures of macromolecules like proteins and nucleic acids. H-bond energies are within the range of thermal motion of molecules at physiological temperature. This facilitates the formation and break…

The History of QSAR

Quantitative Structure Activity Relationship (QSAR) is one of the most important tools in modern drug design. The principle of QSAR is based on the fact that biological activity of a particular chemical compound is directly correlated to its structural and physicochemical characteristics.
Major developments in QSAR are given below. Download PDF