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BB 314 Unit 4: Protein Structure, Function and Regulation
Terms in this set (16)
What are some cellular functions of proteins?
-structure, function, and regulation of the body's tissues and organs
-Enzymes carry out almost all of the thousands of chemical reactions that take place in cells
Primary, secondary, tertiary and quaternary structure of a protein
Primary: linear sequence of amino acids in the polypeptide chain. The primary structure is held together by covalent bonds such as peptide bonds
Secondary: The most common types of secondary structures are the α helix and the β pleated sheet. Both structures are held in shape by hydrogen bonds, which form between the carbonyl O of one amino acid and the amino H of another.
Tertiary: Protein tertiary structure is the three dimensional shape of a protein. The tertiary structure will have a single polypeptide chain "backbone" with one or more protein secondary structures, the protein domains.
Quaternary: quaternary structure is the arrangement of more than one protein molecule in a multi-subunit complex.
Alpha helix and beta sheet
A protein domain is a conserved part of a given protein sequence and (tertiary) structure that can evolve, function, and exist independently of the rest of the protein chain.
What forces are involved in the folding of a protein into its 3-D shape?
-affinity for water
-pH of environment
What kinds of interactions/bonds are involved in the formation of alpha helices and beta
Alpha: Hydrogen and covalent bonds.
Beta: Hydrogen bonds
What covalent bonds are important in stabilizing the tertiary structure of proteins?
What methods are used to find out about the 3-D shapes of proteins?
Methods like X-ray crystallography and NMR (nuclear magnetic resonance) can be used to determine the position of every atom in the protein. The data from these experiments is fed into a computer that can reconstruct the three dimensional shape of the protein in great detail.
How does the structure of a protein relate to its function (in other words, why does shape
This sequence of amino acids is known as the primary structure and dictates the future role of the protein. A change in the primary structure of amino acids therefore affects the protein's function. ... The creation of a specific and unique shape is important in functional proteins such as enzymes.
What factor(s) besides the 3-D shape of the protein is important to its function?
Why is there interest in knowing about the shapes of proteins?
Sequence determines how the protein will fold. The 3D shape is important because proteins work by working directly with other molecules that also have specific shapes. Protein function can be regulated by changing the shape of a protein
What is rational drug design?
• Rational drug design is the use of our knowledge of the structure of a protein to design drugs that can block its action. It is "rational" or based in reason, rather than by guesswork.
Why do cellular reactions have to be regulated?
The management of biochemical reactions with enzymes is an important part of cellular maintenance. Enzymatic activity allows a cell to respond to changing environmental demands and regulate its metabolic pathways, both of which are essential to cell survival.
What are two major ways of regulating the activity of proteins?
Allosteric regulation: Allosteric Regulation: The Allosteric site (allo = different) and the binding of the allosteric ligand at this site changes the protein's overall shape. Or different molecule at a different spot.
Phosphorylation: Phosphorylation: covalent addition of a phosphate group on to the side chain of specific amino acids in a protein. The addition of a negatively charged phosphate group to the side chains can change the interaction of these side chains with other parts of the protein, subtly altering the protein's shape and thus its activity. Basically, a negative charge is placed on the side chain where there wasn't a negative charge before. Extremely common in cells
What do they have in common? How are they different?
In allosteric regulation, the regulatory molecule is not covalently attached to the protein, it merely binds in a reversible manner to the protein. Phosphorylation is the covalent addition of a phosphate group to specific amino acid side chains. This alters the activity of the protein that is phosphorylated.
Define active site, allosteric site, substrate, product.
Active Site: A region on an enzyme that binds to a protein or other substance during a reaction.
Allosteric Site: The place on an enzyme where a molecule that is not a substrate may bind, thus changing the shape of the enzyme and influencing its ability to be active.
Substrate: the surface or material on or from which an organism lives, grows, or obtains its nourishment, or the substance on which an enzyme acts.
Product: something "manufactured" by an organelle (or whatever)