A new drug is developed which selectively cleaves covalent
bonds between two sulfur atoms of non-adjacent amino acids
in a polypeptide chain. Which level of protein structure in
affected molecules would be most directly affected by the
drug
The tertiary structure of the affected protein molecules would be most directly affected by the drug as it is the level of protein structure where the non-adjacent amino acids are held together by disulfide bonds formed between the sulfur atoms. Disrupting these bonds would cause a structural change in the protein, altering its function.
Albumin is a large protein which circulates freely in human plasma. Another
type of protein, called aquaporins, act as a channel for water to enter and exit a
cell, and are located within the lipid bilayer of a cell’s plasma membrane. Based
on their physiological locations, how would the tertiary structure of these two
proteins mostly likely compare?
a. Albumin has more of nonpolar core with nonpolar out layer while
aquaporins have a more polar core with polar outer layer.
b. Albumin has more of nonpolar core with polar outer later while
aquaporins have more polar core with nonpolar outer layer.
c. Albumin has more polar core with non polar outer layer while
aquaporins have a more of non polar core with polar outer layer
d. Albumin has more polar core with polar outer layer while aquaporins
have a more of non polar core with non polar outer layer
c. Albumin has more polar core with non polar outer layer while aquaporins have a more non polar core with polar outer layer.
Albumin is a soluble protein that circulates freely in blood plasma, so it needs to be water-soluble. Therefore, it has a polar (hydrophilic) core that can interact with water molecules and a non-polar (hydrophobic) outer layer that interacts with other non-polar molecules in the body.
Aquaporins, on the other hand, are membrane proteins that need to interact with the non-polar lipid bilayer of the cell membrane in order to function. Therefore, they have a non-polar (hydrophobic) core that can interact with the lipid bilayer and a polar (hydrophilic) outer layer that interacts with water molecules.
The level of protein structure most directly affected by the drug that selectively cleaves covalent bonds between two sulfur atoms of non-adjacent amino acids in a polypeptide chain is the tertiary structure.
To determine which level of protein structure would be most directly affected by the drug, we need to understand the different levels of protein structure.
Proteins have four levels of structure: primary, secondary, tertiary, and quaternary.
1. Primary structure: This level refers to the linear sequence of amino acids in a polypeptide chain. The primary structure is determined by the genetic information encoded in the DNA. It is held together by peptide bonds between adjacent amino acids.
2. Secondary structure: This level describes the local folding patterns within a polypeptide chain. The two most common types of secondary structure are alpha-helices and beta-sheets. These structures are formed by hydrogen bonding between the backbone atoms (i.e., the amino and carboxyl groups) of the amino acids.
3. Tertiary structure: This level represents the overall three-dimensional shape of a polypeptide chain. It is determined by the interactions between amino acid side chains, such as hydrophobic interactions, hydrogen bonding, disulfide bonds, and electrostatic interactions.
4. Quaternary structure: This level refers to the arrangement of multiple polypeptide chains (subunits) in a protein complex. Proteins with quaternary structure are composed of two or more polypeptide chains held together by various interactions.
Now, coming back to the question, the drug selectively cleaves covalent bonds between two sulfur atoms of non-adjacent amino acids in a polypeptide chain. Covalent bonds in proteins are generally involved in the tertiary structure, where sulfur atoms from cysteine residues can form disulfide bonds. These disulfide bonds are important for stabilizing and maintaining the three-dimensional structure of the protein.
Therefore, the most directly affected level of protein structure by this drug would be the tertiary structure. By cleaving the covalent bonds between sulfur atoms, the drug would disrupt the stabilizing disulfide bonds, leading to alterations or unfolding of the protein's three-dimensional structure.