Quiz - Amino Acids, Peptides, Proteins - 3 | Amino Acids, Peptides and Proteins

Leucine, with its hydrophobic aliphatic R group, is more likely to be found in the interior of a globular protein to avoid contact with water. Hydrophobic residues tend to be sequestered away from the aqueous environment, contributing to the protein's overall tertiary structure.

Naturally occurring amino acids in enzymes are exclusively L-amino acids. This chirality is crucial for the formation of proper protein secondary, tertiary, and quaternary structures, which in turn determine enzyme function.

Peptide bonds form between the amino group of one amino acid and the carboxyl group of another, resulting in the release of a water molecule. This is a dehydration synthesis reaction and is fundamental to the formation of dipeptides, polypeptides, and ultimately proteins.

At physiological pH, amino acids exist predominantly as zwitterions, where the amino group is protonated (-NH₃⁺) and the carboxyl group is deprotonated (-COO^-), resulting in equal numbers of positive and negative charges in the molecule.

The primary purpose of the Hell-Volhard-Zelinsky reaction is the conversion of carboxylic acids into a racemic mixture of α-amino acids via an α-haloacid.

In the Strecker synthesis mechanism, the cyanide ion acts as a nucleophile, reacting with the iminium intermediate to form α-amino nitriles.

The resolution method in amino acid synthesis is used to separate racemic mixtures, containing equal amounts of both enantiomers, into their individual enantiomers. This process allows for the isolation of optically pure amino acids, which are essential for various applications. However, this method is associated with drawbacks such as high cost, time consumption, and wastage of starting material.

In automated peptide synthesis, amino acids are activated in situ by the addition of a coupling reagent such as DCC, which facilitates the formation of peptide bonds in a repeatable and efficient manner.

In the enantioselective synthesis of amino acids, a chiral reagent, such as a catalyst containing a BINAP moiety, is employed to promote the formation of one desired enantiomer over the other. This approach relies on the non-superimposable 3D structure of the chiral catalyst to selectively favor the desired configuration, resulting in high enantioselectivity.

The Edman degradation method is employed to determine the sequence of amino acids in a peptide. It involves cleaving one amino acid at a time from the N-terminal end of the peptide, identifying the cleaved amino acid, and repeating the process to sequence the entire peptide.