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CαN
CαO Cα
N
Cα
O
Cis/Trans Isomerization: Proline
trans cis
Energy difference between these forms is small.
Nearly all Xaa-Pro linkages are biosynthesized in the trans form.
~10% of these peptide bonds are in the cis form in globular proteins.
Interconversion catalyzed by peptidyl prolyl cis-trans isomerases
Stereo space-filling representation of an α helical segment of sperm whale myoglobin (its E-helix) as determined by X-ray crystal
structure analysis.
Comparison of the two polypeptide helices that occasionally occur in proteins with the commonly occurring α helix.
Stereo space-filling representation of the 6-stranded antiparallel pleated sheet in jack bean concanavalin A as determined by crystal
X-ray analysis.
Polypeptide chain folding in proteins illustrating the right-handed twist of sheets: bovine carboxypeptidase A.
Polypeptide chain folding in proteins illustrating the right-handed twist of sheets: chicken muscle triose phosphate isomerase.
( barrel)
The two-stranded coiled coil: view down the coil axis showing the interactions between the nonpolar edges of the α helices.
The two-stranded coiled coil: side view in which the polypeptide back bone is represented by skeletal (left) and
space-filling (right) forms.
The amino acid sequence at the C-terminal end of the triple helical region of the bovine α1(I) collagen chain.
X-Ray structure of the triple helical collagen model peptide (Pro-Hyp-Gly)10 in which the fifth Gly is replaced by Ala. (a) Ball and stick
representation.
X-Ray structure of the triple helical collagen model peptide (Pro-Hyp-Gly)10 in which the fifth Gly is replaced by Ala. (b) View along
helix axis.
X-Ray structure of the triple helical collagen model peptide (Pro-Hyp-Gly)10 in which the fifth Gly is replaced by Ala. (c) A schematic
diagram.
Sections through the electron density map of diketopiperazine calculated at the indicated resolution.
The 2D proton NMR structures of proteins: a NOESY spectrum of a protein presented as a contour plot with
two frequency axes 1 and 2.
The 2D proton NMR structures of proteins: NMR structure of a 64-residue polypeptide comprising the Src protein SH3 domain.
Representations of the X-ray structure of sperm whale myoglobin: the protein and its bound heme are drawn in stick form.
Representations of the X-ray structure of sperm whale myoglobin: a diagram in which the protein is represented by its computer-
generated Cα backbone.
8 helices
Representations of the X-ray structure of sperm whale myoglobin: a computer-generated cartoon drawing.
Representations of the x-ray structure of sperm whale myoglobin: a diagram in which the protein is represented by its computer-
generated Cα backbone.
H-helix
The H helix of sperm whale myoglobin. (a) A helical wheel representation in which the side chain positions about the α helix are
projected down the helix axis onto a plane.
One subunit of the enzyme glyceraldehyde-3-phosphate dehydrogenase from Bacillus stearothermophilus.
two domains
X-ray structure of the C-terminal domain of bovine - crystallin: a topological diagram showing how its two Greek key motifs are
arranged in a barrel.
X-ray structure of the C-terminal domain of bovine - crystallin: the 83-residue peptide backbone displayed in ribbon form.
X-ray structure of the enzyme, peptide-N4-(N-acetyl--D-glucosaminyl)asparagine amidase F from Flavobacterium
meningosepticum.
X-ray structure of the enzyme, peptide-N 4-(N-acetyl--D-glucosaminyl)asparagine amidase F from Flavobacterium
meningosepticum.
Topological diagrams of (a) carboxypeptidase A and (b) the N-terminal domain of glyceraldehyde-3-phosphate dehydrogenase.
X-ray structures of open sheet-containing enzymes: dogfish lactate dehydrogenase, N-terminal domain (residues 20-163 of this
330-residue protein).
A GRASP diagram of human growth hormone (helps predict protein interactions with charged molecules)
Graphical Representationand Analysis of
SurfaceProperties
Melting temperature of RNase A as a function of the concentration of various salts.
chaotropic
strengthen hydrophobic interactions
Weaken hydrophobicinteractions
Hofmeister series
Some possible symmetries of proteins with identical protomers. (a) Assemblies with the cyclic symmetries C2, C3, and C5.
Some possible symmetries of proteins with identical protomers. (b) Assemblies with the dihedral symmetries D2, D4, and D3.
Some possible symmetries of proteins with identical protomers. (c) Assemblies with T, O, and I symmetries.
X-ray structure of glutamine synthetase from Salmonella typhimurium - view down 6-fold symmetry axis
X-ray structure of glutamine synthetase from Salmonella typhimurium - view down one of the 2-fold symmetry axes