How Water Contributes To The Structure And Behavior Of Biological Molecules

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Introduction

Water,H2O, is one of the most important chemical compounds on earth, and is commonly referred to as the basis of life on earth, because it is used in all type of chemical and biological processes, e.g. solvent, protein folding, stability of nucleic acids etc. Water is found in 3 states (solid, liquid, and gas), and is the most abundant naturally occurring substance on earth, covering 75% of the earth surface.

Structure

Water consists of 2 hydrogen atoms and 1 oxygen atoms, (held together by covalent bonds between the O-H atoms) and 2 lone pair of electrons on the oxygen atom, resulting in the formation of a bent shape with a bond angle of 104.5⁰. These 2 lone pair of electrons means that water has a tetrahedral structure where oxygen is bonded to 4 hydrogen atoms; 2 covalent bonds and 2 hydrogen bonds (General Chemistry, 2011).

Hydrogen bonding ‘is a specific type of dipole-dipole interaction between the hydrogen atom in a polar bonds, and an electronegative O, N or F atom’ (Quotes from General Chemistry, 2011 page 405), and is the strongest type of intermolecular force. Hydrogen bonds in water (Figure 1) mean that water has a high specific heat capacity, this is because, as hydrogen bonds are strong a large amount of heat (increases the kinetic energy of water molecules), is needed to break them, however water can absorb a large amount of heat and its temperature only increases slightly, and is the reverse when heat is released i.e. its temperature only decreases slightly (General Chemistry, 2011). The presence of hydrogen bonds between water molecules, allowing them to stick together mean shows that water is highly cohesive (Biochemistry, 2011). A special type of cohesion is surface tension, in which te...

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC372788/pdf/microrev00039-0112.pdf

http://www.ncbi.nlm.nih.gov/pubmed/3307919

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1262463/pdf/biophysj00088-0020.pdf

http://www.lsbu.ac.uk/water/protein2.html - protein folding and denaturing

http://www.lsbu.ac.uk/water/protein.html - Protein Hydration

http://www.lsbu.ac.uk/water/nucleic.html - Nucleic acid

http://www.biomedcentral.com/1471-2199/12/21 - Protein Diversity

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=4335444 – Behavior of water

http://www.exobiologie.fr/index.php/vulgarisation/chimie-vulgarisation/the-role-of-water-in-the-structure-and-function-of-biological-macromolecules/ - The role of water in the structure and function of biological macromolecules

Wikipedia – Protein folding, Water, Hydrophobic Interactions, Solvent

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