Show
The correct answer option is (C). The polar amino acids (AAs) are the ones that are usually found on the folded protein’s outer surface because these AAs are hydrophilic (water-loving) in nature. Out of the given AAs in the question, Asp (aspartic acid) is the polar one, and thus, it is most likely to be found on the protein’s surface. Hence, the correct option is (C). The hydrophobic (water-repelling) amino acids are the ones that are usually found in the protein’s interior. Some examples of these AAs include Ile (isoleucine), Val (valine), Phe (phenylalanine), and Met (methionine). Hence, option (A), option (B), option (D), and option (E) are incorrect. Which of the following statements regarding peptide bonds is least accurate? Favored conformation of peptide bonds is with the sequential alpha carbons in cis position. Correct: Trans position Which of the following amino acids is found most frequently at beta turns in the secondary structures of proteins? Proline Which of the following secondary structures is most likely to be found in a membrane embedded portion of a protein? An alpha helix composed entirely of hydrophobic residues The amino acid that would be expected to be located within the interior of a folded protein suspended in an aqueous buffer would be Isoleucine because it's non polar The amino acid that would disrupt the ordered structure of a folded alpha helix would be Proline because of the compound formation The amino acid that could be modified by addition of a phosphate group would be Tyrosine because of the aromatic ring A histidine residue is in the active site of an enzyme and has a glutamate residue nearby, What effect would the nearby glutamate have on the pea of the histidine? Glutamate is an acidic amino acid because it has a negative charge and would favor a positively charged amino acid like Histidine. Favoring a positively charged form makes histidine a weaker acid causing the pka to go up. Experiments on denaturation and renaturation after the reduction and deoxidation of the disulfide bonds in the enzyme RNase have shown that: the primary sequence of RNase is sufficient to determine its specific secondary and tertiary structure The side chain of serine could interact with the side chain of ________ using a ________ His, hydrogen bond For a globular protein that is found in the cytosol, ___ would most likely be found in the proteins interior while ___ would most likely be found on the surface. Leu, Ser Which of the following interactions would be involved in quaternary structure? Hydrogen bonds, hydrophobic interactions, disulfide bonds, and salt bridges In a site directed mutagenesis experiment a specific Leu residue in a protein was changed to various other residues. Predict which if the following changed would have the greatest impact on the structure and function of the protein. Asp Which of the following is the driving force for protein folding? Hydrophobic effect Molecular chaperones assist unfolded proteins by Protecting the unfolded protein from inappropriate protein protein interactions as the protein is synthesized . Inducing rapid and precise folding of proteins into their correct conformations Protein domains are independently folded regions with a tertiary function, often with a specific and unique function Amino acids with R groups that have H-bond potential are Serine, Glutamate, Tyrosine and threonine (all have OH groups) A Ramachandran plot shows: shows the favored and disfavored phi and psi angles. pH < pKa favors COOH and NH3+ pH > pKa favors COO- and NH2 Hydrogen bond donor N-H group (positive charge) Hydrogen acceptor C=O group (negative charge) Phi angle (Φ): angle of rotation about the single bond between the nitrogen and the alpha carbon atom Psi angle (Ψ): angle of rotation about the single bond between the alpha carbon and the carbonyl carbon atom Petide bond is between C=O and N-H Primary structure The first level of protein structure; the specific sequence of amino acids making up a polypeptide chain. The final secondary structure is stabilized by the formation of what? the formation of H-bonds between amino acids on the polypeptide chain Alpha helix the spiral shape resulting from the coiling of a polypeptide in a protein's secondary structure Beta sheets H bonds between distant amino acids; rigid structure. parallel or antiparallel Antiparallel beta sheets 2 or more beta strands that are running in opposite directions. · The amino acids are all lined up so that the amino acid on one strand forms two H-bonds with the amino acid on the opposite strand. Parallel beta sheets two or more beta strands run in the same direction. The amino acids don't like up and the H-bond is slightly different. Beta Turns and Loops Pro and Gly prevalent in beta turns. secondary structure of protein protein structure is formed by folding and twisting of amino acid chain through beta sheets and alpha helices tertiary structure of protein protein structure is formed when the twists and folds of the secondary structure fold again to from a larger 3D structure What is the most important interaction in tertiary structure? Hydrophobic effect and hydrophobic interactions plays the most important role in helping polypeptide take on tertiary structure. Majority of proteins fold and create tertiary structure in aqueous solutions. Hydrophobic effect amino acids with hydrophobic side chains like valine, alanine, isoleucine, methionine, and leucine will tend to be inside the protein. The amino acids with hydrophilic side chains like lysine, arginine and aspartate will tend to be found on the outside of the protein. 3D protein structure When forming a protein the hydrophobic side chains will be in the middle, whole the hydrophilic side chains will surround the hydrophobic side chains on the outside when in an aqueous solution. Van der Waal interactions the non-polar amino acids of the protein core interact with one another via their instantaneous dipoles. Certain proteins, especially the ones that are supposed to be extracellular, cross links can form within the polypeptide. The cross links are normally disulfide bonds between two cysteine amino acids. The cysteine units help conform the protein into its tertiary structure. Ionic bonds can form between those amino acids that have opposite charges like lysine and aspartate amino acids. Quaternary structure of protein Larger proteins that consist of two or more polypeptide chains can contain a fourth level of structure. Combination of 2nd and 3rd protein structures dimer, trimer, tetramer · are normally held together by noncovalent interactions, but sometimes they can be held together by colvalent interactions called disulfide bonds. Which of the following amino acid residues would most likely be buried in the interior of water soluble, globular protein? Phenylalanine (non polar) Ionic positive and negative amino acids form salt bridges Hydrophobic Nonpolar amino acids H-bond H-donor and H-acceptors (amino acids with OH groups) aromatic tyrosine and tryptophan motif repetitive super secondary structure (combination of alpha helices and beta sheets) domain independently folded regions with a characteristic and specific function How do proteins adopt their final tertiary and quaternary structures? Hydrophobic effect drives protein folding. Spontaneous process G<0 higher S alfinsen experiment ribonuclease placed in urea and beta mercaptoethanol, denatured all 3 and 2 structures, plus reduced disulfide bonds. Denaturants were removed protein folded back, and resumed function. Urea disrupts H-bonds within backbone and R groups Change in pH acid and base content. Disrupts electrostatic interactions Heat general disruption in energy Ionic strength adding or taking away salt affects the acidic or basic R groups Detergents breaks down protein protein interactions Denaturants 1. urea the process of protein folding involves progressive stabilization of correct secondary structural intermediates and unfolding of incorrect structures until the final structure is attained. Requirements for molecular chaperones interacts with and stabilizes non-native forms of proteins and not part of the final assembly of proteins Function: assist folding and assembly of proteins beta mercaptoethanol breaks disulfide bonds within secondary and tertiary structures Salting out When adding salt like sodium chloride or ammonium sulfate into the aqueous protein solution, the solubility of the protein begins to decrease. When we reach a certain salt concentration value, the protein will become insoluble and will precipitate out of the solution. Salting out takes place because the salt ions break the hydrogen bonds that are stabilizing the individual protein molecules Dialysis remove and exchange a buffer solutions Can have a molecular weight cut off. Whatever is bigger or smaller than the molecular weight cut off will be in the solution, while desired protein will be inside bag Gel filtration separation based on size. Small proteins are the last to separate and will spend the most amount of time in the beads. The bigger proteins are the proteins that elute first and spend no time in the beads. As a mixture of proteins travel through the column, the small proteins enter the porus beads while the larger proteins can't fit into the internal volume of the beads. The large proteins reach the bottom first, while small proteins emerge last. Cation exchange chromatography separation based on charge have positively charged protein and negatively charged beads Anion exchange chromatography separation based on charge have negatively charged protein and positively charged beads Affinity chromatography based on affinity for a ligand (binds your protein with high specificity) Example: you have a mixture of 3 proteins and we know that the protein we want isolate binds to glucose molecules. We can modify the beads so that glucose groups will bind to the surface of the beads. As the 3 proteins travel down, the one with high affinity for glucose will bind to the beads and the others will go through. Once the other proteins are removed, you can wash the desired protein with a glucose solution, causing a competition for the active site of the protein. This will cause the protein to detach form the beads. How do you track your protein of interest? 1. Assay SDS-PAGE Separates by size Runs negative to positive Top: Negative (large particles) Bottom: Positive (small particles) Large particles are retained. Which of the following best describes the state of a protein whose pI = 7, when in a solution whose pH = 9? The protein will have a net positive charge When put at a certain pH if the pka is higher than desired pH it will be positive When put at a certain pH if the pka is lower than desired pH it will be negative SDS-PAGE electrophoresis When the protein is denatured, SDS anions attach onto the side chains of amino acids. Since SDS anions have a negative charge, this means that by attaching onto the protein, the protein is made negatively charged. As the SDS-protein complexes move down the gel, they are dragged by the electric field. Since they are all negative, they will move down. Larger proteins move more slowly because they experience a greater friction than smaller proteins. The larger proteins will be higher up along the slab than smaller proteins. Which amino acid is most likely to be found on the interior of a soluble protein?Glycine and alanine have the highest occurrence among the buried amino acids in membrane proteins, whereas leucine and alanine are the most common buried residue in soluble proteins.
Which of the following amino acids is most likely to be found in the interior of a cytosolic protein?Introduction to Biochemistry
Out of the given AAs in the question, Asp (aspartic acid) is the polar one, and thus, it is most likely to be found on the protein's surface. Hence, the correct option is (C). The hydrophobic (water-repelling) amino acids are the ones that are usually found in the protein's interior.
Which of these amino acids is most likely to be found near the interior of a membrane?The interior of the phospholipid bilayer is a hydrophobic environment; therefore, leucine and other hydrophobic amino acids are more commonly found in the membrane-spanning portions of transmembrane proteins.
Which of the following amino acids is likely to be found in the interior of a globular protein?So, the amino acids present on exterior of globular protein are aspartic acid and lysine while amino acids present on inside of globular protein are valine and phenylalanine.
|
Which of the following amino acids is most likely to be found in the interior of the protein in aqueous solution?
zusammenhängende Posts
Urheberrechte © © 2024 nguoilontuoi Inc.
