Hydropathy index

Hydropathy index-  

It is related to amino acids. It represents the hydrophobic properties of amino acid side chains.The larger the number in the scale the more hydrophobic the amino acid .

HYDROPATHY SCALES (a measure of hydrophobicity) -- a way of quantitating whether a 20 amino acid segment might be hydrophobic enough to be a transmembrane helix. More hydropathy index means more energy is required to stabilize in the aquous environment .

• More + numbers indicate more hydrophobic R groups;
•  more - numbers indicate more hydrophilic R groups.

The free energy change accompanying movement of amino acid side chain from hydrphobic solvent into water .

Charged (polar )-Exergonic Aromatic and Aliphatic-Endergonic 

Hydropathy plots (plot of hydropathy index vs. residue number where the residue number is actually the average hydropathy value for a "sliding window" of, say, 7 residues, moving down the protein from N to C-terminus -- for example, average values for residues 1-7, then for 2-8, then 3-9, etc. are plotted.

• Depends on the hydropathy scale being used (i.e., what nonpolar solvent was used for the partitioning experiments to determine relative solubilities in H₂O vs. nonpolar solvent); zero is always the midpoint of being neither hydrophilic or hydrophobic, and negative values are more hydrophilic, while positive values are more hydrophobic.

                                           Image source credit- http://slideplayer.com/slide/7360690/

Thank you for visiting my blog.Please feel free to share your comment on this article ,Please subscribe and share the articles to get more such articles.