Search results
Results from the WOW.Com Content Network
Amino acid. Structure of a typical L -alpha-amino acid in the "neutral" form. Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. [1] Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. [2]
Hydrophobicity scales. Hydrophobicity scales are values that define the relative hydrophobicity or hydrophilicity of amino acid residues. The more positive the value, the more hydrophobic are the amino acids located in that region of the protein. These scales are commonly used to predict the transmembrane alpha-helices of membrane proteins.
The portion of the membrane proteins that are attached to the lipid bilayer (see annular lipid shell) consist mostly of hydrophobic amino acids. [12] Membrane proteins which have hydrophobic surfaces, are relatively flexible and are expressed at relatively low levels. This creates difficulties in obtaining enough protein and then growing crystals.
The hydrophobic effect is the observed tendency of nonpolar substances to aggregate in an aqueous solution and to be excluded by water. [1][2] The word hydrophobic literally means "water-fearing", and it describes the segregation of water and nonpolar substances, which maximizes the entropy of water and minimizes the area of contact between ...
In proteins with globular folds, hydrophobic amino acids tend to be interspersed along the primary sequence, rather than randomly distributed or clustered together. [ 25 ] [ 26 ] However, proteins that have recently been born de novo , which tend to be intrinsically disordered , [ 27 ] [ 28 ] show the opposite pattern of hydrophobic amino acid ...
For instance, if a stretch of about 20 amino acids shows positive for hydrophobicity, these amino acids may be part of alpha-helix spanning across a lipid bilayer, which is composed of hydrophobic fatty acids. On the converse, amino acids with high hydrophilicity indicate that these residues are in contact with solvent, or water, and that they ...
Alpha helix. Three-dimensional structure of an alpha helix in the protein crambin. An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix). The alpha helix is the most common structural arrangement in the secondary structure of proteins. It is also the most extreme type of local structure ...
Leucine zipper. "Overhead view", or helical wheel diagram, of a leucine zipper, where d represents leucine, arranged with other amino acids on two parallel alpha helices. A leucine zipper (or leucine scissors[1]) is a common three-dimensional structural motif in proteins. They were first described by Landschulz and collaborators in 1988 [2 ...