Protein Structure

Question 1

Primary Protein Structure

Answer 1

Listed from N terminus to C terminus. Stabilized by covalent bonds b/w AA (Amino group attaches to OH group in carboxylic acid)

Question 2

Secondary Structure

Answer 2

Result of Hydrogen Bonding between neighboring amino acids Alpha-helices: peptide chain coils clockwise around a central axis. bonds are from carbonyl oxygen atom to the amide hydrogen every 4 residues. i.e: Keratin (hair, nails, skin) Beta-pleated sheets: Parallel or antiparallel, carbonyl oxygen bonded to amine hydrogen (hydrogen bonding). como un acordeón (so they are more compacted) R groups point above and below the plane. i.e Fibroin which makes silk fibers

Question 3

Tertiary Structure

Answer 3

Results on the folding dictated by the R side chains polarity. (Hydrophobic inside) amid a carboxyl group are hydrophilic. Stabilization is formed by a combination of electrostatic interaction and H-bonding. acid-base interaction can form charged R groups which can create salt bridges. i.e two cysteine molecules can form a disulfide bond (S-S) by oxidation (lose 2 + and 2 e-)

Question 4

Quarternary Structure

Answer 4

Not all proteins have quaternary structure. Is the combination of different subunits. i.e Immunoglobulins and Hemoglobin *Letters-Word-Sentence-Paragraph *Conjugated proteins can have lipid or carb tags. Which can direct them to the cell membrane or an organlle and serve as a cofactor i.e hemoglobin needs the heme group for oxygen to bind

Question 5

SDS-PAGE and Reducing SDS PAGE

Answer 5

SDS-PAGE: is an electrophoresis method that allows protein separation by mass.

Reducing SDS PAGE: Reducing conditions in this context means using beta-mercaptoethanol (2-ME) or dithiothreitol (DTT) to reduce disulfide bridges in proteins

OXIDATION REQUIRED TO MAKE DISULFIDE BONDS

Question 6

Multimeric Proteins

Answer 6

two or more polypeptide chain

Homodimeric = 2 same chains