Robert Singer (producer) directed at least one television show.
Alpha sheet -LRB- also known as alpha pleated sheet or polar pleated sheet -RRB- is an atypical secondary structure in proteins , first proposed by Linus Pauling and Robert Corey in 1951 .. secondary structure. secondary structure. Linus Pauling. Linus Pauling. Robert Corey. Robert Corey. The hydrogen bonding pattern in an alpha sheet is similar to that of a beta sheet , but the orientation of the carbonyl and amino groups in the peptide bond units is distinctive ; in a single alpha strand , all of the carbonyl groups are oriented in the same direction on one side of the pleat , and all of the amino groups are oriented in the same direction on the opposite side of the sheet .. beta sheet. beta sheet. carbonyl. carbonyl. amino. amino. peptide bond. peptide bond. Thus the alpha sheet accumulates an inherent separation of electrostatic charge , with one edge of the sheet exposing negatively charged carbonyl groups and the opposite edge exposing positively charged amino groups .. carbonyl. carbonyl. amino. amino. electrostatic charge. electrostatic charge. Unlike the alpha helix and beta sheet , the alpha sheet configuration does not require all component amino acid residues to lie within a single region of dihedral angles ; instead , the alpha sheet contains residues of alternating dihedrals in the traditional right-handed -LRB- αR -RRB- and left-handed -LRB- αL -RRB- helical regions of Ramachandran space .. beta sheet. beta sheet. amino. amino. alpha helix. alpha helix. amino acid. amino acid. Ramachandran space. Ramachandran plot. Although the alpha sheet is only rarely observed in natural protein structures , it has been speculated to play a role in amyloid disease and it was found to be a stable form for amyloidogenic proteins in one set of molecular dynamics simulations .. protein. protein. amyloid. amyloid. molecular dynamics. molecular dynamics. Alpha sheets have also been observed in X-ray crystallography structures of designed peptides .. X-ray crystallography. X-ray crystallography