Proteins Flashcards
What are 3 examples of proteins?
Enzymes
Structural Proteins
Transport Proteins
What is an enzyme-like function?
Amelogenin acting as a scaffold for the mineralization of enamel
What is the typical composition of bone?
Mineral (Hydroxyapatite 50-70%) Protein (Mostly collagen; 20-40%) Non-collagen proteins (typically 1-2%) Lipids (3%) Water (5-10%)
The linkage between amino acids in protein is an _____ linkage?
amide
Two amino acids hooked together is a ______ bond
Peptide
Most proteins are ___ - ______ amino acids long
50 - 2000
Each protein sequence produces its own _______
Function
Omega
specifies protein backbone dihedral angle
Rotation around the peptide bond is restricted by ________. This simplifies deducing secondary structures.
Resonance
Alpha helices
Spiral staircases with amino acid steps
How many steps per alpha helice turn?
3.6 steps
What handed are alpha-helices?
right-handed
How do side chains project on alpha helices?
up and out
What is the distance between
0.15 nm
What is the distance between neighboring B strand residues?
0.35 nm
How do beta strands pair?
donor-acceptor backbone
B-strands are fully ______ conformations
extended
B - strands can align both _______ and ______ to form B- sheets
parallel
antiparallel
Silk fibroin is all __ sheet
Beta
Amyloid of _______ disease is almost all __ sheet
Alzheimer
Beta
__ - keratin (intracellular fibers of skin) is all __ helix (coiled-coil)
alpha
alpha
Myosin (protein for muscle contraction) is mostly __ helix
alpha
Some _______ - forming proteins are disordered before forming amyloid
amyloid
Amyloid
starch like but is actually a protein, presence in almost all neurogenerative diseases
Parallel B-sheet can wrap as a helix __ - helix
Beta
The collagen triple helix is 1/3 _____.
Glycine
The collagen triple helix has inter-helical -bonds
H
What is the hydrogen bond donor of the collagen triple helix?
NH2 of glycine
What is the three dimensional structure of the polypeptide chain stabilized by?
hydrogen bonds, electrostatic and hydrophobic interactions and certain cases by disulfide linkage between cysteine residues
Quaternary structure
refers to the arrangement of protein subunits in a multinumeric complex
What is one of the most well known and highly characterized multi-protein complexes?
Hemoglobin heterotetramer
The partial double bond character of the peptide bond restricts neighboring groups to a single ______.
plane