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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.
All beta-barrels can be classified in terms of two integer parameters: the number of strands in the beta-sheet, n, and the "shear number", S, a measure of the stagger of the strands in the beta-sheet. [3] These two parameters (n and S) are related to the inclination angle of the beta strands relative to the axis of the barrel. [4] [5] [6]
This domain has a 3-layer structure, and contains a beta-sandwich fold of unusual topology, and contains a putative tRNA-binding structural motif. [2] In Thermus thermophilus, both the catalytic alpha- and the non-catalytic beta-subunits comprise the characteristic fold of the class II active-site domains.
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.
In molecular biology, protein fold classes are broad categories of protein tertiary structure topology. They describe groups of proteins that share similar amino acid and secondary structure proportions.
Two Rossmann folds in Cryptosporidium parvum lactate dehydrogenase, with NAD+ bound. A beta-alpha-beta motif is composed of two beta strands joined by an alpha helix through connecting loops. The beta strands are parallel, and the helix is also almost parallel to the strands. This structure can be seen in almost all proteins with parallel strands.
The immunoglobulin domain, also known as the immunoglobulin fold, is a type of protein domain that consists of a 2-layer sandwich of 7-9 antiparallel β-strands arranged in two β-sheets with a Greek key topology, [1] [2] consisting of about 125 amino acids. The backbone switches repeatedly between the two β-sheets.
There is a hypothesis that the Walker A phosphate binding motif can be evolutionarily related to Rossman's fold phosphate binding motif because of the shared principles in the location of the binding loop between the first β-strand and α-helix in the αβα sandwich fold and positioning of the functionally important aspartate on the tip of ...