Amino Acids, Peptides, and Proteins

What is the defining structural feature of the 20 common amino acids found in proteins, with the exception of proline?

For the amino acid Glycine, which has pK1 = 2.34 and pK2 = 9.60, what is its isoelectric point (pI)?

Which class of amino acids contains R groups that are the most hydrophilic?

How is a peptide bond formed between two amino acids?

What is the first step in any protein purification procedure from a tissue or microbial cells?

In ion-exchange chromatography, how are proteins separated?

What is the primary function of sodium dodecyl sulfate (SDS) in SDS-PAGE?

According to Table 3-1, which amino acid has a hydropathy index of 4.5, indicating it is highly hydrophobic?

The Edman degradation procedure is used to determine the amino acid sequence of a polypeptide. How does this procedure work?

What is a major source of free energy used by enzymes to lower the activation energies of reactions?

Which level of protein structure is defined as the sequence of amino acids in a polypeptide chain, including disulfide bonds?

Which enzyme would cleave a peptide bond on the carboxyl (C) side of Phenylalanine, Tryptophan, or Tyrosine residues?

The peptide Ser–Gly–Tyr–Ala–Leu has a common abbreviation. What is the correct one-letter code abbreviation for this pentapeptide, following convention?

A protein with a molecular weight of 66,000, like serum albumin, is analyzed. What is the approximate number of amino acid residues in this protein?

What is the term for a complete, catalytically active enzyme together with its bound coenzyme and/or metal ions?

In two-dimensional electrophoresis, what two properties are used to separate a complex mixture of proteins?

What term refers to proteins from different species that are homologous and have the same function?

What is the typical yield for adding one amino acid in the automated chemical peptide synthesis process developed by R. Bruce Merrifield, and what is the approximate overall yield for a 100-residue peptide with this efficiency?

A mixture of the peptides Lys-Gly-Ala-Gly and Asp-Gly-Ala-Gly is to be separated by ion-exchange chromatography at pH 7.0. Which peptide will elute first from a cation-exchange column?

The uncommon amino acid 4-hydroxyproline is found in significant amounts in which fibrous protein?

What is the primary characteristic of L stereoisomers of amino acids, according to the Fischer convention?

A researcher is studying human cytochrome c and titin. According to Table 3-2, how many amino acid residues and polypeptide chains do these two proteins have, respectively?

What is 'specific activity' and how does it change during a successful protein purification?

Which amino acids are primarily responsible for the characteristic strong absorbance of light by most proteins at a wavelength of 280 nm?

What is the isoelectric point (pI) for Histidine, given its pKa values are pK1=1.82, pKR=6.00, and pK2=9.17?

Two Cysteine residues can be readily oxidized to form a covalently linked dimeric amino acid. What is this dimeric amino acid called?

In size-exclusion chromatography, a mixture of proteins (A, B, and C with molecular weights of 100,000, 50,000, and 25,000, respectively) is applied to a column. In what order will they elute?

Which of the following is an example of a conjugated protein?

What is the primary difference between homologous proteins classified as paralogs versus orthologs?

Which amino acid, when its R group is ionized, can serve as a proton donor or acceptor in enzyme-catalyzed reactions near physiological pH?

Which of the following describes a method to irreversibly break disulfide bonds in a protein for sequencing purposes?

What is a key advantage of using mass spectrometry over the Edman degradation for protein sequencing?

In the process of dialysis, how are proteins separated from small solutes?

What is the approximate occurrence in proteins for the amino acid Lysine (Lys) according to Table 3-1?

Which technique is used to determine the isoelectric point (pI) of a protein by establishing a pH gradient in a gel?

The chemical reagent cyanogen bromide is used to fragment polypeptide chains. According to Table 3-6, at which residue does it cleave the peptide bond?

What is a 'fusion protein' in the context of protein chemistry?

According to the properties listed in Table 3-1, what is the molecular weight (Mr) of the amino acid Proline (Pro)?

The Lambert-Beer law is expressed as log(I0/I) = ecl. What does the term 'absorbance' (A) represent?

A protein is described as oligomeric. What does this term imply?

Using tandem mass spectrometry (MS/MS), a peptide is fragmented, and a series of y-type ions is detected. What does this set of peaks represent?

What is the primary function of affinity chromatography in protein purification?

Which of the following amino acids has a side chain that can form a disulfide bond?

A student needs to estimate the concentration of a purified protein solution. Which property, primarily attributed to aromatic amino acids, allows for this estimation using spectrophotometry?

What is the pKa of the R group for Arginine, as listed in Table 3-1?

When purifying a protein, what is the purpose of the 'salting out' step, typically using ammonium sulfate?

What is the defining characteristic of a consensus sequence?

If a peptide has a net positive charge at a given pH, toward which electrode will it migrate during electrophoresis?

What is the primary distinguishing feature between simple proteins and conjugated proteins?

What is the approximate molecular weight (Mr) of the amino acid Tryptophan (Trp), according to Table 3-1?