BIOMOLECULES AND ENZYMES

Detailed explanation-1: - turns (also -bends, tight turns, reverse turns, Venkatachalam turns) are the most common form of turns-a type of non-regular secondary structure in proteins that cause a change in direction of the polypeptide chain. They are very common motifs in proteins and polypeptides.

Detailed explanation-2: -(a) Bends or turns are most likely to occur at residues 7 and 19 because Pro residues are often (but not always) found at bends in globular folded proteins. A bend may also occur at the Thr residue (residue 4) and, assuming that this is a portion of a larger polypep-tide, at the Ile residue (residue 1).

Detailed explanation-3: -For instance, the amino acid proline is sometimes called a “helix breaker” because its unusual R group (which bonds to the amino group to form a ring) creates a bend in the chain and is not compatible with helix formation 4start superscript, 4, end superscript.

Detailed explanation-4: -The Beta Turn Turns generally occur when the protein chain needs to change direction in order to connect two other elements of secondary structure. The most common is the beta turn, in which the change of direction is executed in the space of four residues.