Search results
Results from the WOW.Com Content Network
The beta sheet (β-sheet, also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands ( β-strands ) connected laterally by at least two or three backbone hydrogen bonds , forming a generally twisted, pleated sheet.
This means that 2 adjacent residues in the primary structure must form the same hydrogen bonding pattern. If the helix or sheet hydrogen bonding pattern is too short they are designated as T or B, respectively. Other protein secondary structure assignment categories exist (sharp turns, Omega loops, etc.), but they are less frequently used.
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.
The alpha helix spiral formation An anti-parallel beta pleated sheet displaying hydrogen bonding within the backbone. Formation of a secondary structure is the first step in the folding process that a protein takes to assume its native structure.
Porins are composed of beta sheets (β sheets) made up of beta strands (β strands) which are linked together by beta turns (β turns) on the cytoplasmic side and long loops of amino acids on the other. The β strands lie in an antiparallel fashion and form a cylindrical tube, called a beta barrel (β barrel). [2]
Beta pleated sheets are formed by backbone hydrogen bonds between individual beta strands each of which is in an "extended", or fully stretched-out, conformation. The strands may lie parallel or antiparallel to each other, and the side-chain direction alternates above and below the sheet.
The TIM barrel (triose-phosphate isomerase), also known as an alpha/beta barrel, [1]: 252 is a conserved protein fold consisting of eight alpha helices (α-helices) and eight parallel beta strands (β-strands) that alternate along the peptide backbone. [2] The structure is named after triose-phosphate isomerase, a conserved metabolic enzyme. [3]
Being a cytoplasmic protein requires that the protein be globular in structure, that is largely non-polar on the inside and polar on the outside, so as to be solubilized by water. Hsp90 contains nine helices and eight anti-parallel beta pleated sheets, which combine to form several alpha/beta sandwiches.