BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Proline also destabilizes -helices because of its irregular geometry; its R-group bonds back to the nitrogen of the amide group, which causes steric hindrance. In addition, the lack of a hydrogen on Proline’s nitrogen prevents it from participating in hydrogen bonding.

Detailed explanation-2: -Proline is established as a potent breaker of both alpha-helical and beta-sheet structures in soluble (globular) proteins. Thus, the frequent occurrence of the Pro residue in the putative transmembrane helices of integral membrane proteins, particularly transport proteins, presents a structural dilemma.

Detailed explanation-3: -When proline is found in an helix, the helix will have a slight bend due to the lack of the hydrogen bond. Proline is often found at the end of helix or in turns or loops.

Detailed explanation-4: -amino acids apart, and Rresidues that are amino acids apart would destabilize an alpha helix.

Detailed explanation-5: -Now that there are over 30, 000 protein structures in the Protein Data Bank, it is clear that proline residues are present in -helices, where they often play important roles in the structure and function of the protein.