DNA as Poetry: Multiple Messages in a Single Sequence | HuffPost
What Are Nucleic Acids? You probably hear about proteins, fats, and carbohydrates on a daily basis, and you may even plan your meals. Structure and Function Relationships of Proteins The three-dimensional structure of a protein defines not only its size and shape, but also its function. it created the chen basis for the design of insulin analogues, which turned out to be an invaluable too the study of the structure-function relationships of insulin, .
The native conformation is analogous to a plane with all its parts in the right place: When something happens to knock it out of its native conformation, its effectiveness decreases or gets lost all together. Proteins in their native conformations have multiple levels of structural organization What does a protein in its native conformation look like?
Globular proteins structure and function (article) | Khan Academy
There are four levels of structural organization for proteins in their native conformations. The primary structure of a protein refers to the specific amino acid sequence of the protein, plus the peptide bonds that join each of these amino acids together. In other words, the primary structure of a protein is fixed as soon as the amino acids are linked together. Primary structure is the two-dimensional component of the eventual three-dimensional shape.
The secondary structure of a native conformation refers to the three dimensional organization of the main chain atoms of a protein. The main chain atoms of a protein are the atoms that all amino acids in a protein have in common shown in the picture below in black.
The structure and function of globular proteins
Main chain atoms are named in contrast to side chain atoms, which are the atoms in an amino acid—leucine, say—that distinguish it from another amino acid—isoleucine, for example shown in the picture below in blue. As it happens, the two most common types of secondary structures that occur in the main chain atoms of proteins resemble coils and zigzags.
The coils are called alpha helices. The zigzags are called beta sheets. Different types of proteins have different distributions of alpha helices and beta sheets: The tertiary structure of a native conformation refers to the three dimensional organization of all the atoms—including side chain atoms—in a protein.
Perhaps the best way to visualize what tertiary structure looks like is to imagine taking an amino acid sequence with primary and secondary structure and crumpling it up into a ball.
Just as each type of protein has its own unique primary and secondary structure, it also has its own unique tertiary structure.
The quaternary structure of a native conformation refers to the three dimensional organization of all the atoms in a multi-subunit protein. Multi-subunit proteins consist of two or more individual amino acid chains, each with their own primary, secondary, and tertiary structures.
DNA as Poetry: Multiple Messages in a Single Sequence
The way these individual chains fit together into an overall three dimensional arrangement is called quaternary structure.
Only multi-subunit proteins have quaternary structure. All 4 levels of protein structure are determined by amino acids interacting with each other and their environment Why do native conformations happen? Like anything else, the ultimate explanation involves the laws of physics.
As we already said, amino acids first come together to form primary structures because of attractions between the left and right sides of neighboring amino acids. Similarly, secondary structures form primarily because of attractive and repulsive forces generated by interactions between the main chain atoms of neighboring amino acids.
And, finally, tertiary structure mostly arises from interactions between side chain atoms of amino acids and the water molecules from the surrounding environment.
What does this mean?
Well, the laws of thermodynamics conspire to maximize the free movement of water molecules at the molecular level. It turns out that crumpling proteins up into specific tertiary or quaternary structures maximizes the freedom for water molecules to move. Membranes contain large amounts of lipids, which are notoriously hydrophobic water and oil don't mix.
The membrane-spanning regions of membrane proteins are typically alpha helices, made of hydrophobic amino acids. These hydrophobic regions interact favorably with the hydrophobic lipids in the membrane, forming stable membrane structures. Hemoglobin is a soluble protein - found in the cytoplasm of red blood cells as single molecules - which bind oxygen and carry it to the tissues.
In sickle cell anemia, a mutation in the beta-globin protein of the red blood cell increases its hydrophobicity and causes the mutant protein molecules to stick to each other, avoiding the aqueous environment.
What is the relationship between the poem's structure and its meaning
Chains of hemoglobin change the shape of the red blood cell from round to a sickle shape, which causes the cells to collect in narrow blood vessels. Active site The folding of a protein allows for interactions between amino acids that may be distant from each other in the primary sequence of the protein.
In enzymes, some of these amino acids form a site in the structure that catalyzes the enzymatic reaction. This site, called the active site of the enzyme, has amino acids that bind specifically to the substrate molecule, also called a ligand Fig. In a similar manner, certain sites in cell receptor proteins bind to specific ligand molecules that the receptor recognizes.