21 topics with concise breakdowns: definitions, key facts, and class questions.
Proteins are the primary molecular machines of the body. In this section, we study their architecture: from amino acids and peptide bonds to secondary, tertiary, and quaternary structures. You will learn how structural motifs and the active site are formed, why disulfide bonds are necessary, and how chaperones help proteins fold into the correct shape.
We examine the basics of functioning using classical examples: myoglobin, hemoglobin, immunoglobulins, and the hormone insulin. We will certainly touch upon physicochemical properties, isolation methods (protein chromatography), as well as the processes of denaturation and renaturation. The clinical aspect is vividly illustrated through sickle cell anemia. The anticholinergics that snuck into the list serve as an excellent bridge to understanding how receptor proteins become targets for drugs.
During colloquia, instructors most frequently ask about levels of structural organization, differences between myoglobin and hemoglobin, the structure of the active site, and the essence of denaturation. These topics form a rock-solid foundation for understanding enzymatic catalysis and pharmacology.
In what state are the functional groups of amino acids in the body?
Under physiological conditions, they are ionized: the $\alpha$-amino group turns into a cation ($-NH_3^+$), and the $\alpha$-carboxyl group turns into an anion ($-COO^-$).
What bonds maintain the secondary structure of a protein?
Secondary structure is formed exclusively by hydrogen bonds between the carbonyl ($-C=O$) and amino groups ($-NH-$) of the peptide backbone.
Which bonds are strong covalent bonds in the tertiary structure?
Only disulfide bonds, which form between the SH groups of cysteine residues, are strong covalent bonds.
To which level of structural organization do the "zinc finger" and "leucine zipper" motifs belong?
These elements represent variants of supersecondary protein structure. They are formed due to a specific spatial arrangement of $\alpha$-helices and loops.
What is a prosthetic group?
This is the non-protein part of a conjugated protein, which is firmly and irreversibly bound to its protein core. A striking example is heme, which is part of hemoglobin and cytochromes.
Why is atropine able to bind to receptors instead of acetylcholine?
This is due to their chemical affinity. Atropine has an ester group and a nitrogen-containing fragment, and the spatial arrangement of its functional groups matches the structure of acetylcholine.
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