- Of the following, which amino acid is most likely to be found in position 1 or 4 on α keratin?
A) Phe
B) Ala
C) Lys
D) Trp
E) Pro
B - Ala is likely to be found in keratin 1 or 4 position
- Which of the following amino acids combinations have side chains with groups that have the greatest ability to stabilize the tertiary structure of a protein?
A) Lys and Arg
B) Cys and Glu
C) Glu and Lys
D) Gln and Glu
E) Pro and Asp
C - Glu and Lys - are opposite charges thus can protonate or deprotante
- The low pH found in the gut can enhance the digestibility of dietary protein by causing ___.
A) amide hydrolysis
B) protein denaturation
C) disulfide reduction
D) prion formation
E) cysteine oxidation
B - acid denaturaizes protein
- Which of the following occurs first when folding a disordered polypeptide chain into a
stable protein formation?
A) formation of a low energy state
B) association of ordered subunits
C) aggregation of hydrophobic regions in the protein
D) tertiary structure refinement
E) formation of a low entropy state
C
- For beta-sheets, the terms 'parallel' and 'antiparalllel' refer to ___________.
A) the 'direction' of the associated peptide strands
B) the orientation of the amide cross-links
C) the quaternary structure of the protein
D) the orientation of the hydrogen bonding
D) the topology of the reverse turns
A - direction
- Conventional one dimensional NMR spectroscopy is not generally an effective tool for determination of protein structure because...
I. Proteins (including small proteins) have a high number of hydrogen atoms.
II. NMR requires a high quality protein crystal.
III. The NMR spectra exhibit high peak overlap.
A) I and II
B) II and III
C) I and III
D) I, II, and III
E) III only
C - NMR shows high H atom count and peak overlap
- When comparing similarities among multiple protein structures, which of the following is false?
A) Proteins with the same function from a different species are likely to have similar motifs.
B) Proteins with the same function from different species are likely to be more similar in sequence than in structure.
C) An effective protein motif isl likely be observed in multiple proteins.
D) Proteins with the same motifs are likely to perform similar functions.
E) None of the above statements are false.
B- proteins with same function from diff species are not likely to be more similar in sequence
- The structure and sequence of a protein of unknown function was examined. Which of the following provides the best prediction of the protein's function?
A) the observation of several disordered α helical domains.
B) the observation of multiple protein subunits.
C) the observation of motif known as the Rossmann fold.
D) the observation of a large number of random coil regions.
E) All of the above offer excellent prediction of the protein's function.
C - Rossmann fold is a good prediction of a proteins function
- The Protein Data Bank (PDB) is a database provides structural information about proteins that may be useful for which of the following?
I. A researcher studying the changes in protein fold associated with prions.
II. A researcher classifying structural elements by function.
III A researcher designing a compound to bind tightly to a particular region in the protein.
A) I only
B) II only
C) III only
D) I, II
E) I, II, II
E - PDB shows changes in protein folds, structural elements and specific protein regions
- Noncovalent forces that stabilize protein structure include all of the following except __________.
A) the hydrophobic effect
B) salt bridges
C) electrostatic interactions with metal ions
D) hydrogen bonding
E) disulfide bridges
E - disulf are covalent
