Amino Acid pKa Values

Which amino acid residue has a pKa value closest to physiological pH (~7.4), making it a crucial player in enzymatic catalysis?

The pKa of the alpha-amino group of an amino acid is significantly lower than the pKa of its alpha-carboxyl group.

What is the approximate pKa of the guanidino group in arginine?

The pKa of the side chain of cysteine (Cys-SH) falls in the range of _ to 11 in proteins.

Match the amino acid residue with its approximate pKa range in proteins:

Which of the following ionizable groups has the lowest pKa value?

The pKa values of ionizing groups are identical in model compounds and within the protein environment.

What amino acid possesses an imidazole group?

The side chain of _ has a pKa around 10.4 in model compounds.

Match each amino acid with its corresponding functional group:

How does the microenvironment influence the pKa of an ionizable group within a protein?

Arginine is typically negatively charged at physiological pH.

What is the approximate pKa of the alpha-carboxyl group in model compounds of amino acids?

The pKa of the hydroxyl group in _ can range from 9 to 12 within proteins.

Match each amino acid with its approximate pKa in a small peptide:

Which amino acid contains a thiol group, which can form disulfide bonds?

The pKa of phosphates is consistent within a protein.

What range of pKa values is typical for histidine residues in proteins?

In model compounds, the pKa of the alpha-amino group of an amino acid is approximately _ .

Match each amino acid with its listed pKa:

Which amino acid residue is commonly targeted by ubiquitination?

Phosphorylation involves the addition of a phosphate group to a protein, typically from an ATP molecule.

What molecule donates the acetyl group during acetylation?

The process of adding a myristoyl group to a protein is known as __________.

Match the following covalent modifications with the amino acid residues they commonly target:

Which enzyme is responsible for activating ubiquitin in the ubiquitination process?

Methylation always leads to the activation of the target enzyme.

What is the precursor molecule that provides the adenosine monophosphate (AMP) group in adenylylation reactions?

Which of the following modifications involves the transfer of a fatty acid?

Covalent modifications are always irreversible.

What is the amino acid that is modified during methylation?

Which molecule is released during the acetylation of a protein?

ADP-ribosylation always leads to enzyme inactivation.

Which of the following amino acids can be targeted by phosphorylation?

Adenylylation involves the addition of an AMP moiety to a tyrosine residue.