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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. A β-strand is a stretch of polypeptide chain typically 3 to 10 amino acids long with backbone in an extended conformation .
In biology literature, the term topology is also used to refer to mutual orientation of regular secondary structures, such as alpha-helices and beta strands in protein structure [3]. For example, two adjacent interacting alpha-helices or beta-strands can go in the same or in opposite directions.
These methods were based on the helix- or sheet-forming propensities of individual amino acids, sometimes coupled with rules for estimating the free energy of forming secondary structure elements. The first widely used techniques to predict protein secondary structure from the amino acid sequence were the Chou–Fasman method [ 17 ] [ 18 ] [ 19 ...
The Rossmann fold is a tertiary fold found in proteins that bind nucleotides, such as enzyme cofactors FAD, NAD +, and NADP +.This fold is composed of alternating beta strands and alpha helical segments where the beta strands are hydrogen bonded to each other forming an extended beta sheet and the alpha helices surround both faces of the sheet to produce a three-layered sandwich.
β-Strands Arrows with thickness, about one-quarter as thick as they are wide, showing direction and twist of the strand from amino to carboxy end. β-sheets are seen as unified because neighboring strands twist in unison. Loops and miscellaneous Nonrepetitive loops
Beta-sandwich or β-sandwich domains consisting of 80 to 350 amino acids occur commonly in proteins. They are characterized by two opposing antiparallel beta sheets (β-sheets). [ 1 ] The number of strands found in such domains may differ from one protein to another. β-sandwich domains are subdivided in a variety of different folds.
The individual beta strands are labeled with their traditional designations (for historical reasons, sheet A is not used), highlighting the packing of the BIDG and CHEF four-stranded sheets. [ 1 ] The jelly roll or Swiss roll fold is a protein fold or supersecondary structure composed of eight beta strands arranged in two four-stranded sheets.
The beta hairpin (sometimes also called beta-ribbon or beta-beta unit) is a simple protein structural motif involving two beta strands that look like a hairpin. The motif consists of two strands that are adjacent in primary structure , oriented in an antiparallel direction (the N-terminus of one sheet is adjacent to the C-terminus of the next ...