What is the difference between beta strand and beta sheet?

Answer 1

1. Alpha Helix

• rod like
• CO & NH of the mainchain are hydrogen bonded together, allowing the mainchain to be buried
• n+4 H bonding scheme
• all alpha carbons are H bonded and in line with each other
• R groups are on the outside & backbone on the inside
• always right handed (clockwise)
• can be a single chain (usually less than 45 Angstroms)
• Residues that are 1 & 2 residues apart are on opposite sides, while residues that are 3 & 4 residues apart are on the same side; this allows small steric hindrance
• 1.5 Angstroms rise (from one alpha carbon to the second)
• 100 degree rotation
• 3.6 residues per turn
• Ramachandran diagrams (1) Right handed: can only occur between -60, -60; little hindrance (2) Left handed: +60, +60; large hindrance

2. Beta Sheet

• sheet like
• Beta sheets are formed by linking 2 or more Beta strands by H bonds
• side chain of adjacent residues point in opposite directions
• only trans peptide bonds give R groups on opposite sides
• cannot exist as a single Beta strand; must be 2 or more
• in proteins, 4-5 strands make up a beta sheet; it is possible to be made of more than 10
• 3.5 Angstroms rise between residues
• 7 Angstroms between R groups
• Arrow in pictures always points to the CO group
• can be antiparallel, parallel, or mixed
• anti: 1:1; alpha carbons are completely lined up across from each other; CO & NH of adjacent strands are H bonded together; chains are in opposite directions
• parallel: strands are in the same direction; NH group of the first chain is bonded to the CO of the 2nd chain through H bond, then move two residues to the right and the CO of the first chain is H bonded to the NH of the 2nd chain.
• Ramachandran diagrams: exists between -60 to -120, 100-190

Answer 2

A beta strand is a single chain of amino acids with a specific conformation, while a beta sheet is formed when two or more beta strands align and hydrogen bond with each other. Beta strands are the building blocks of beta sheets, which are a common secondary structure in proteins.

Answer 3

Alpha helix and beta pleated sheets both are held together with H bonds between carbonyl O and amino N. Alpha helix specifies with residues bind. Beta pleated sheets can happen between any 2 residues.

Answer 4

Stabilized by hydrogen bonds, hydrogen bonding between amides groups

Polypeptide secondary structures.

Answer 5

Beta sheets consist of beta strandsconnected laterally by at least two or three backbone hydrogen bonds, forming a generally twisted, pleated sheet.

Answer 6

Secondary structure