Search results
Results from the WOW.Com Content Network
A transmembrane domain (TMD, TM domain) is a membrane-spanning protein domain.TMDs may consist of one or several alpha-helices or a transmembrane beta barrel.Because the interior of the lipid bilayer is hydrophobic, the amino acid residues in TMDs are often hydrophobic, although proteins such as membrane pumps and ion channels can contain polar residues.
In protein structures, a beta barrel (β barrel) is a beta sheet (β sheet) composed of tandem repeats that twists and coils to form a closed toroidal structure in which the first strand is bonded to the last strand (hydrogen bond). Beta-strands in many beta-barrels are arranged in an antiparallel fashion.
A table comparing four different scales for the hydrophobicity of an amino acid residue in a protein with the most hydrophobic amino acids on the top A number of different hydrophobicity scales have been developed.
Schematic diagram of the 2D structure of aquaporin 1 depicting the six transmembrane alpha-helices and the five interhelical loop regions A-E The 3D structure of aquaporin Z highlighting the 'hourglass'-shaped water channel that cuts through the center of the protein. Aquaporin proteins are composed of a bundle of six transmembrane α-helices ...
The portion of the membrane proteins that are attached to the lipid bilayer (see annular lipid shell) consist mostly of hydrophobic amino acids. [13] 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.
Protein–protein interactions (PPIs) are physical contacts of high specificity established between two or more protein molecules as a result of biochemical events steered by interactions that include electrostatic forces, hydrogen bonding and the hydrophobic effect. Many are physical contacts with molecular associations between chains that ...
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, 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 ...
Sterics, bond strain, and angle strain also play major roles in the folding of a protein from its primary sequence to its tertiary structure. Single tertiary protein structures can also assemble to form protein complexes composed of multiple independently folded subunits. As a whole, this is called a protein's quaternary structure.