Download CH 460 Dr. Muccio What are the 4 levels of protein structure and

CH 460
Dr. Muccio
What are the 4 levels of protein structure and describe each. Do proteins with
similar structures usually have similar functions?
Primary - amino acid sequence
Secondary – helices, sheets, turns, loops
Tertiary – 3d folding
Quaternary – organization of 3d subunits
Yes usually (not always), similar structure and similar function correlate
_____ reactions lead to ____ bond formation, or peptide bonds. Draw an arrow to the
peptide bond in the figure below.
Aldol; covalent
Condensation; amide
Redox; amide
Condensation; covalent
None
Peptides are named from their ____ end to their ____ end. So in the peptide “His-SerGln” which is on the amino end? The carboxy?
Amino to carboxy, His, Gln
What are the four types of secondary structure? What are they stabilized by? Can
you draw them?
Alpha helix – h-bonds in the same chain, few steric interaction
Beta sheets - h-bonds between neighboring beta-strands, few steric
interaction
Beta turn – ONE h-bond, few steric interactions
Loop/random – no h-bonds, few steric interactions
When proteins are unfolded, they _____ to their native state which is ______ energy
Do not return; high
Return; high
Do not return; low
Return; low
What are the forces that favor the native state?
Hydrophobic forces – nonpolar amino acids will point towards the
interior of proteins with fewer hydrophilic ones pointing out towards
water
Van der waals – due to the tight packing
H-bonds – form h-bonds in the interior of proteins
CH 460
Dr. Muccio