- Hydrophilicity plot
A hydrophilicity plot is a
quantitative analysis of the degree ofhydrophobicity orhydrophilicity ofamino acid s of aprotein . It is used to characterize or identify possible structure or domains of a protein.The plot has amino acid sequence of a protein on its
x-axis , and degree of hydrophobicity and hydrophilicity on itsy-axis . There are a number of methods to measure the degree of interaction ofpolar solvent s such as water with specific amino acids. For instance, theKyte-Doolittle scale indicates hydrophobic amino acids, while theHopp-Woods scale measures hydrophilic residues.Analyzing the shape of the plot gives information about partial structure of the protein. For instance, if a stretch of about 20 amino acids shows positive for hydrophobicity, then this indicates that these amino acids may be part of
alpha-helix spanning across alipid bilayer , which is composed of hydrophobic fatty acids. Conversely, amino acids with high hydrophilicity indicate that these residues are in contact with solvent, or water, and that they are therefore likely to reside on the outer surface of the protein.
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