Quiz - Amino Acids, Peptides, Proteins - 2 | Amino Acids, Peptides and Proteins

Organic Chemistry 3 - Quiz - Amino Acids, Peptides, Proteins - 2


What chemical process involves the conversion of a carboxylic acid into a racemic mixture of α-amino acids via an α-haloacid?

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


Which method is predominantly used in automated peptide synthesis?

Automated peptide synthesis is typically done using solid-phase synthesis techniques. Two protective group strategies are commonly used: Fmoc (9-fluorenylmethyloxycarbonyl) and Boc (tert-butyloxycarbonyl). The solid-phase synthesis allows for sequential addition of amino acid residues to a growing chain anchored to a resin.


Which level of protein structure is stabilized by disulfide bonds?

Disulfide bonds form between the side chains of cysteine residues and stabilize the tertiary structure of a protein. These covalent bonds contribute to the three-dimensional folding of the protein that is critical for its function.


During peptide sequencing, what would be the consequence of skipping the Edman degradation process?

Edman degradation is a method used to sequentially remove one residue at a time from the amino end of a peptide. Skipping the Edman degradation step would mean that no amino-terminal residues would be cleaved off for identification, hindering the sequencing process.


What distinguishes α-amino acids from other amino acids?

α-amino acids are characterized by having a chirality center on the α-carbon, except for glycine, which has two hydrogen atoms as its side chain.


What is the isoelectric point (pI) of an amino acid?

The isoelectric point (pI) is the pH at which an amino acid exists primarily in its neutral zwitterionic form, where the number of positive and negative charges in the molecule are equal.


In the context of secondary structure, which interactions are most decisive in forming an α helix?

The α helix is a common motif in the secondary structure of proteins, stabilized by hydrogen bonds formed between the carbonyl oxygen of one amino acid and the amide hydrogen of another that is four residues down the chain. This pattern of hydrogen bonding is essential for the helical structure.


What role does the peptide bond play in defining the primary structure of proteins?

The primary structure of a protein is defined by its unique sequence of amino acids, which are connected by peptide bonds. The peptide bond is a covalent linkage formed between the carboxyl group of one amino acid and the amino group of the next, and it is crucial for the linear structure of proteins.


What is the primary method used in automated peptide synthesis?

The Merrifield synthesis, a solid-phase synthesis method, is commonly used in automated peptide synthesis. In this approach, Fmoc-protected amino acids are sequentially added to an insoluble polymer, and the polypeptide chain is synthesized step by step. The final peptide is cleaved from the polymer after assembly.


What is the connection between protein structure and biological function?

The 3D structure of a protein, encompassing its primary, secondary, tertiary, and quaternary structures, is intimately related to its biological function. The specific shape and folding pattern allow a protein to interact with other molecules such as substrates, inhibitors, DNA, or other proteins, thus determining its function within the biological system.