Which of the following is NOT a feature of the peptide bond?
Six atoms, including two alpha-carbons are in the plane of each peptide bond.
The peptide bond is highly polar.
The peptide bond has 10% double bond character.
The trans conformation is much mor
The peptide bond has 10% double bond character.
it actually 40%
In an alpha-helix, which amino acid residue makes a hydrogen bond to the 3rd residue?
6th
4th
7th
1st
7th
The pattern is n -> n+4.
Regular secondary structures are often joined by stretches of peptides called reverse turns or beta _____
bends
The spatial arrangement of subunits of a protein is called its______ structure
quaternary
The three-dimensional structures of proteins are most commonly determined by X-ray crystallography, or by nmr studies.
True
False
true
Which of the following statements is true because of the hydrophobic effect?
Uncharged polar residues S, T, N, Q, and Y are usually found on the surface of proteins, but may also be found in the interior.
The interior of proteins is packed very densely.
C
Nonpolar residues V, L, I, M, and F are found in the interior of proteins.
The arrangement of protomers in an oligomeric protein is called the_____ structure
quaternary
Which pairs of amino acid side chains could not interact in the interior of a protein by hydrogen bonding?
Ser, His
Asp, Asn
Gln, Thr
Ala, Lys
Ala, Lys
The sequences of proteins are more likely to be conserved than their structures during evolution.
True
False
false
greek key motif
Which of the following series of amino acids is MOST likely to be at the surface of a water-soluble globular protein?
.........val-ala-val-glu-val.........
.........met-phe-pro-ile-leu........
.........tyr-phe-gly-asn-leu.........
.........met-cys-pro-ala
........glu-asn-ser-thr-arg.........
A peptide bond is all of the following except:
A bond that displays resonance
An ester bond
A planar bond
An amide bond
When it is formed water is removed from an amino group and a carboxylic acid group
an ester bond
How Long is an 80 amino acid alpha helix?
FACTS to KNOW: One turn: 3.6 aa's, 5.4 � long
80 �
54 �
120 �
36 �
160 �
120 A
Which is the more stable beta-sheet: parallel or antiparallel?
Parallel, due to a high concentration of proline residues, promoting more linear H-bonds
Antiparallel, due to a more elongated structure than parallel sheets
Antiparallel, due to more linear H
Antiparallel, due to more linear H-bonds and a high concentration of Ala and Gly
A "Greek Key" describes a type of structure motif. What kind of structure is it?
A mixed beta-sheet
A mixed alpha/beta structure
A parallel beta-sheet
A cluster of alpha-helices
An antiparallel beta-sheet
An antiparallel beta-sheet
A motif in the glycolysis enzyme hexokinase could contain which of the following?
beta-turn
right-handed alpha helix
quarternary structure
parallel beta-sheet
beta-turn
right-handed alpha helix
parallel beta-sheet
Which of the following statements about quaternary structure is TRUE?
Quaternary structure is defined as the arrangement of polypeptide backbones in proteins with four subunits.
Quaternary structure exists only in monomeric proteins containing more than o
Quaternary structure is stabilized by the same types of noncovalent interactions as tertiary structure.
Which of the following is likely to form first during the process of protein folding?
alpha helices
quarternary structure
native fold
tertiary structure
alpha helices
Which statement about the structure of collagen is FALSE?
In the collagen repeating sequence (Gly-X-Y)n, 5-hydroxylysine (Hyl) sometimes appears at the Y position.
The three helices of collagen form a left-handed superhelix.
Mutations of Type I collagen i
The three helices of collagen form a left-handed superhelix.
Which of the following best describes the cause of Creutzfeld-Jakob Disease (a disease which human can develop with symptoms similar to those of mad cow disease)?
Ingestion of ammonium salts.
The serious side effects of experimental treatment with Quinacr
Aggregation of a misfolded protein.
In a Ramachandran diagram, a larger area represents sterically allowed torsion angles of ? and ? that are allowed in _____ rather than in ______ because there is greater opportunity for separation of amino acid side chains.
secondary structure...tertiary
? sheet... alpha helix
Which of the following changes would not alter the functional characteristics of keratin?
Increasing the number of residues per turn to 4.1 while maintaining the same amino acid sequence.
Substitution of a hydrophilic amino acid for a hydrophobic amino ac
all of the above
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?
Lys and Arg
Cys and Glu
Glu and Lys
Gln and Glu
Pro and Asp
Glu and Lys
Imagine that a researcher treated a protein with a high concentration of a chaotropic agent. Which of the following is the most likely result of the treatment?Please select all that apply.
Nonpolar portions of the protein become more soluble.
The protein
Nonpolar portions of the protein become more soluble.
The protein begins to denature.
When comparing similarities among multiple protein structures, which of the following is false?
Proteins with the same function from a different species are likely to have similar motifs.
Proteins with the same function from different species are likely t
Proteins with the same function from different species are likely to be more similar in sequence than in structure.
Which of the following would be most stable based on the information you have learned about protein structure?
A loop region with 8 amino acids.
A ? sheet region made up of amino acids Val, Ile, Phe.
An helix made up of Cys, Pro, and Phe.
A ? hairpin with
? sheet region made up of amino acids Val, Ile, Phe.
A helix has hydrogen bonds between the carbonyl group from residue "n" and the amino group of residue "n+6," which of the following is TRUE?
It has 3.6 residues per turn.
It is a random coil, not a helix.
It is an helix.
It has more residues per turn than
It has more residues per turn than an helix.
Examine the three sequences below for collagen-like proteins. If hydrogen bonding were the most important feature in determining strength in fibrous proteins, which of the following sequences likely has the highest melting temperature and why? (Note: Flp
1" because Hyp has OH groups.
Examine the three sequences below for collagen-like proteins and their melting temperatures (Tm). (Note: Flp = fluoroproline; Hyp = hydroxyproline) Based on this data, what is the most important feature in determining the strength of the collagen protein?
Inductive effect.
In a Ramachandran diagram the region representing the angles of ? and ? that correspond to those commonly made by an amino acid that favors a left-handed helix are different from those angles commonly made by an amino acid that favors right-handed helix f
Groups which would normally undergo high steric hindrance in the right-handed arrangement are separated maximally in the left-handed arrangement.
Protein dynamics is a field of study that examines the movements with in a protein. Which type of protein structure determination would be most useful to study this type of change?
X-ray absorption spectroscopy
X-ray crystallography
Nuclear Magnetic Reson
NMR
n a protein, the most conformationally restricted amino acid is ______; the least conformationally restricted is ______.
Trp, Gly
Met, Cys
Pro, Gly
Ile, Ala
Ala, Pro
Pro, Gly
Which of these characteristics does not describe the ? sheet?
Amino acid side chains are located both above and below the sheet.
? sheets have a pleated edge-on appearance.
They can exist in either parallel or antiparallel configurations.
The sheets conta
Parallel ? sheets containing fewer than five chains are the most common.
Which of the following is true regarding crystalline proteins?
The diffractive pattern observed during X-ray exposure to the crystal can be used to calculate the electron density map of the crystalline protein.
The larger region indicating electron densit
The diffractive pattern observed during X-ray exposure to the crystal can be used to calculate the electron density map of the crystalline protein.
Many crystallized enzyme proteins remain catalytically active
In general molecular chaperone proteins function by
mediating disulfide bond formation.
synthesizing new proteins when one is misfolded.
preventing premature folding by binding hydrophobic regions of the protein.
enhancing salt bridge formation.
none of t
preventing premature folding by binding hydrophobic regions of the protein.
The classic experiment demonstrating that reduced and denatured RNase A could refold into the native form demonstrates that _______.
1� structure can determine 3� structure.
denaturation does not disrupt protein 2� structure.
disulfide bonds do not stabil
1� structure can determine 3� structure.