Three Dimensional Structure Of Proteins
Three-Dimensional Structure of
Proteins
Rotation around the -Carbon in a
Polypeptide
A Sterically Nonallowed
Conformation
The Helix and Pleated Sheet
Conformationally
allowable structures where backbone is optimally Hbonded (linear Hbonds).
Helix (3.613 Helix):
•3.6 residues/turn
•Rise = 0.15 nm/ residue •13-atom hydrogenbonded loop
Linus Pauling and
Robert Corey, 1950
Pleated Sheet:
•Anti-parallel or parallel •2.0 residues/”turn”
•0.34 nm/residue
(anti-parallel) or
0.32 nm/residue
(parallel)
Linus Pauling and
Robert Corey, 1951
Antiparallel and Parallel Pleated
Sheets
Other Secondary Structures
310 Helix:
•3 residues/turn
•0.20 nm/residue
•10-atom
hydrogen-bonded loop Helix (4.416 Helix):
•4.4 residues/turn
•0.12 nm/residue
•16-atom hydrogenbonded loop
Idealized Helices
Hydrogen Bonding Patterns for
Different Helices
Ramachandran Plot
G.N. Ramachandran, 1963
Fibrous Proteins*
Proteins with an elongated or filamentous form, often dominated by a single type of secondary structure over a large distance.
Most fibrous proteins are associated with connective tissue and help provide mechanical strength to the tissue.
*
vs. globular proteins
Structure of Keratin and Keratin-Type
Intermediate Filaments
Keratin is a principal component of hair, horn, nails and feathers. Adjacent polypeptide chains also crosslinked by disulfide bonds.
Disulfide bond patterns between are what determine whether human hair is straight or curly.
Coiled-Coil -Helical Dimer of
Keratin
Amphipathic helices:
Residues a, d, a’ and d’ hydrophobic, other residues hydrophilic.
Structure of Silk Fibroin
Silk made by silkworms and spiders. Composed of microcrystalline array of antiparallel
pleated sheets where each strand has alternating Gly and Ala or Ser residues. Structure of Collagen Fibers
Collagen is the most abundant vertebrate protein and the major stress-bearing component of connective tissue
(bone, teeth, cartilage, tendon)
and
Proteins
Rotation around the -Carbon in a
Polypeptide
A Sterically Nonallowed
Conformation
The Helix and Pleated Sheet
Conformationally
allowable structures where backbone is optimally Hbonded (linear Hbonds).
Helix (3.613 Helix):
•3.6 residues/turn
•Rise = 0.15 nm/ residue •13-atom hydrogenbonded loop
Linus Pauling and
Robert Corey, 1950
Pleated Sheet:
•Anti-parallel or parallel •2.0 residues/”turn”
•0.34 nm/residue
(anti-parallel) or
0.32 nm/residue
(parallel)
Linus Pauling and
Robert Corey, 1951
Antiparallel and Parallel Pleated
Sheets
Other Secondary Structures
310 Helix:
•3 residues/turn
•0.20 nm/residue
•10-atom
hydrogen-bonded loop Helix (4.416 Helix):
•4.4 residues/turn
•0.12 nm/residue
•16-atom hydrogenbonded loop
Idealized Helices
Hydrogen Bonding Patterns for
Different Helices
Ramachandran Plot
G.N. Ramachandran, 1963
Fibrous Proteins*
Proteins with an elongated or filamentous form, often dominated by a single type of secondary structure over a large distance.
Most fibrous proteins are associated with connective tissue and help provide mechanical strength to the tissue.
*
vs. globular proteins
Structure of Keratin and Keratin-Type
Intermediate Filaments
Keratin is a principal component of hair, horn, nails and feathers. Adjacent polypeptide chains also crosslinked by disulfide bonds.
Disulfide bond patterns between are what determine whether human hair is straight or curly.
Coiled-Coil -Helical Dimer of
Keratin
Amphipathic helices:
Residues a, d, a’ and d’ hydrophobic, other residues hydrophilic.
Structure of Silk Fibroin
Silk made by silkworms and spiders. Composed of microcrystalline array of antiparallel
pleated sheets where each strand has alternating Gly and Ala or Ser residues. Structure of Collagen Fibers
Collagen is the most abundant vertebrate protein and the major stress-bearing component of connective tissue
(bone, teeth, cartilage, tendon)
and