Beta sheet

The β sheet (also β-pleated sheet) is a commonly occurring form of regular secondary structure in proteins, first proposed by Linus Pauling and Robert Corey in 1951. It consists of two or more amino acid sequences within the same protein that are arranged adjacently and in parallel, but with alternating orientation such that hydrogen bonds can form between the two strands. The amino acid chain is almost fully extended throughout a β strand. The N-H groups in the backbone of one strand establish hydrogen bonds with the C=O groups in the backbone of the adjacent, parallel strand(s). The cumulative effect of multiple such hydrogen bonds arranged in this way contributes to the sheet's stability and structural rigidity and integrity. The α-C atoms of adjacent strands stand 350 picometres (0.35 nm) apart.

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The side chains from the amino acid residues found in a β sheet structure may also be arranged such that many of the adjacent sidechains on one side of the sheet are hydrophobic, while many of those adjacent to each other on the alternate side of the sheet are polar or charged (hydrophilic).

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Some sequences involved in a β sheet, when traced along the backbone, take a hairpin turn in orientation (direction), sometimes through one or more prolines.

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Beta sheets actually are not flat like the name would indicate. The strands that make up the structure are upon closer observation actually very loosely wound right hand helices. This is a consequence of the phi and psi rotational angles that are repeated across the backbound of the peptide strands.

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Secondary structure: Secondary structure in biochemistry and structural biology describes the general three-dimensional form of local regions or overall shape of biopolymers. It does not, however, refer to specific positions in three-dimensional space, which are considered to be tertiary structure. The secondary struct...

Protein: A protein (in Greek πρωτεϊνη = first thread) is a complex, high-molecular-weight organic compound that consists of amino acids joined by peptide bonds. Proteins are essential to the structure and function of all living cells and viruses....

Linus Pauling: Linus Carl Pauling (February 28, 1901 – August 19, 1994) was an American physical chemist, widely regarded as the premier chemist of the twentieth century. Pauling was a pioneer in the application of quantum mechanics to chemistry, and in 1954 was awarded the Nobel Prize in chemistry for his w...

Beta sheet related Images and Photos (experimental)

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