Beta sheet anti-parallel

For polypeptide, the B program provides options for building various protein conformations including 3-10 helix, alpha helix, alpha helix (L-H), beta sheet (anti-prl), beta sheet (parallel), various beta turns, extended, gamma turns, omega helix, pi helix, polyglycine, and polyproline. Choose the desired conformation and isomer (l or d) and then add amino acids from N-terminus to construct polypeptide chain. 

This common fold variously contains from four to nine anti-parallel four-stranded beta sheets. These are arrayed radially with a geometry similar to a ship s propeller, each propeller blade being composed of four anti-parallel strands, each slighdy twisted in the same orientation. The height or... 

Liu et al. have described the solution structure of a mutant of the homodimer protein transcription factor 1, TFl. The dimeric core, consisting of the N-terminal helices and beta sheets, is more tightly packed than wire type, and this might be responsible for its increased thermal stability. Also, Gordon-Smith et al reported the dimeric structure of a C-terminal fragment of Bovine IFl, which inhibits the hydrol) ic action of the FIFO ATP synthase in mitochondria under anaerobic conditions. Most imusually, the molecule forms an anti-parallel coiled-coil in which three histidine residues occupy key positions at the dimer interface. ... 

Figure A3.1 Strands of beta sheet. The two strands of polypeptide lying alongside one another are able to form multiple hydrogen bonds, stabilising the structure. The adjacent strands here are anti-parallel (running in opposite direction). It is also possible to have parallel strands, but the linking hydrogen bonds are then slightly bent (and therefore weaker) unlike the structure shown, in which the H-bonds are perpendicular to the strands.

The cast SELP-47K films are not mechanically stable after hydration [65, 67] and it is therefore necessary to stabilize its structure. Methanol induces the crystallization of the silklike blocks, leading to aqueous insolubility, and improves the mechanical properties by the conversion of less-ordered conformations into more ordered anti-parallel beta-sheet structures [87,88]. Under uniaxial tensile stress-strain, fully hydrated treated films exhibited an ultimate... 

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