beta sheet

(redirected from Beta-sheet)
Also found in: Dictionary.

beta sheet

n.
A secondary structure that occurs in many proteins and consists of two or more parallel adjacent polypeptide chains arranged in such a way that hydrogen bonds can form between the chains. Also called beta pleated sheet, pleated sheet.

beta sheet

A protein configuration resulting from the alignment of multiple adjacent beta strands and formation of hydrogen bonds between them. The beta sheet is a major secondary protein structure motif elucidated by Pauling and Corey, which consists of polypeptide chains in sheets laid side-by-side and are almost completely extended, with an axial distance of 35 nm vs an axial distance of 15 nm in the helix. The PS is stabilised by hydrogen bonds between NH and CO groups of different polypeptide strands; adjacent molecules may run in the same direction (parallel) or in the opposite (antiparallel) direction—e.g., silk fibroin. The PS is a tertiary structure elucidated by X-ray crystallography and seen by EM; it can be produced experimentally by treating Bence-Jones proteins with enzymes, and is a structure typical of amyloidosis. The PS may be seen by the Congo red stain with polarising light to reveal the characteristic apple-green birefringence.
 
EM
Extracellular 700–1000 nm in diameter, fine complex non-branching fibrils.

beta sheet

A protein structure in which parallel layers of linked peptides are folded across each other. This structure is characteristic of amyloid proteins.
See also: sheet
References in periodicals archive ?
Most beta-sheet breakers have an extremely short half-life and poor blood-brain barrier penetration.
For unknown reasons, in the brain of the Alzheimer's patients, the amyloid protein implicated in AD folds into a particular secondary structure called beta-sheet conformation.
Serono's achievement in starting this clinical trial is a significant milestone in the development of the Axonyx beta-sheet breaker technology," stated Marvin S.
Claudio Soto, Head of Molecular Neuropathology at the Serono Pharmaceutical Research Institute in Switzerland presented data on the beta-sheet breaker compounds that he designed for the treatment of Alzheimer's Disease (AD).
We are pleased to see how Serono has developed the beta-sheet concept and is progressing this novel approach for AD in their preclinical studies," stated Marvin S.
Researchers at the Massachusetts Institute of Technology's (MIT's) Center for Materials Science and Engineering say the key to silk's pound-for-pound toughness, which exceeds that of steel, is its beta-sheet crystals, the nano-sized cross-linking domains that hold the material together.
They found that an unusual arrangement of hydrogen bonds - the "glue" that stabilizes the beta-sheet crystals - play an important role in defining the strength of silk.
Among the latest achievements is the synthesis of beta-sheet proteins.
The tiny beta-sheet crystals, as well as filaments that join them, are arranged in a structure that resembles a tall stack of pancakes, but with the crystal structures within each pancake alternating in their orientation.
In prions, the innocuous form of a protein often contains helical twists that can be converted to flat beta-sheets (although this can be a normal form for proteins too).
Melatonin production reduces as we age (Figure 4) and elderly people with AD have half the blood levels of melatonin as normal people of the same age; this is particularly relevant because melatonin is important for inhibiting the aggregation of [beta]-amyloid protein into [beta]-sheets; (41) the [beta]-amyloid protein, which is the most commonly implicated marker of AD, is most neurotoxic and most resistant to proteolytic degradation when it aggregates into beta-sheets, thus affecting normal brain function.
Transient rigid beta-sheets form, then morph into floppy protein loops, which finally take the form of more beta-sheets.