Special Amino Acids

Insulin is a peptide hormone composed of two separate peptides this includes a looped A chain that is bound to itself via a covalent bond and a linear B chain. Which of the following peptide sequences corresponds to the looped region of the insulin A chain?

Unlike the cytosol the Golgi apparatus is maintained under oxidizing conditions this would allow for:

Substitution with which of the following amino acids within an alpha-helix would lead to the largest decrease in alpha-helix stability?

Because of their high volumetric catalytic activity, in addition to their high chemical and thermal resistances, oxidation generated cross-linked enzyme crystals (CLECs) are an excellent choice for application as immobilized biocatalysts. However, CLECs must have sufficient mechanical stability and retain a large portion of their enzymatic activity to efficiently process immobilisates. Which amino acid residue is most likely used to generate CLECs?

Adapted from: Marta Kubiak et al., Structure-Based Modeling of the Mechanical Behavior of Cross-Linked Enzyme Crystals, Crystals 2022, CC-BY SA 4.0

Aromatic amino acid hydroxylase 1 (AAH1) produces levodopa, a precursor to the catecholamine neurotransmitter dopamine, by converting which of the following amino acids into levodopa?

The optical rotation of four different pure amino acid samples was measured. Sample 1 rotated plane polarized light by 12 degrees clockwise, sample 2 didn’t rotate plane polarized light, sample 3 rotated plane polarized light by 34 degrees counterclockwise, and sample four rotated plane polarized light by 4 degrees counterclockwise. Based on these measurement which of the following samples corresponds to pure glycine?

Branched chain amino acid aminotransferases would be able to catalyze transamination reactions on all of the following EXCEPT?

Off center parallel pi stacking interactions could occur between which two amino acids?