Download Protein Structure

From: Protein Data Bank PDB ID: 1B0E
Kalus, W., Zweckstetter, M., Renner, C., Sanchez, Y., Georgescu, J., Grol, M., Demuth, D., Schumacher, R., Dony, C., Lang, K., Holak, T. A.: structure of
the IGF-binding domain of the insulin-like growth factor-binding protein-5 (IGFBP-5): implications for IGF and IGF-I receptor interactions. EMBO J 17
 Diverse
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functions related to structure
Structural components of cells
Motor proteins
Enzymes
Antibodies
Hormones
Hemoglobin/myoglobin
Transport proteins in blood
 Amino
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acids
Amino group (NH2)
Carboxyl group
(COOH)
 20
amino acids make up
protein
 8 essential amino acids
(must be eaten in diet)

9 in infant (histidine)
5
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bonds or forces determine structure
Peptide bond
Hydrogen bond
Disulfide bond
Ionic bond
Hydrophobic force
 Peptide
bond joins
amino acids
 Bond at both ends
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Increases range of
possible proteins
1.0 x 1026 peptides can
be formed from 20
amino acids
 Linear
sequence of amino acids forms
primary structure (long chain of amino acids)
 Sequence essential for proper physiological
function
 Replacement
of a
single glutamine
amino acid with valine
in one chain of
hemoglobin alters the
structure and function
of the protein
Peptide
chains fold into
secondary structures to become
more compact:
  - helix
  - pleated sheet
 Secondary
structures fold and pack together to
form tertiary structure

Usually globular shape
 Tertiary
structure stabilized by bonds between R
groups (i.e. sidechains)
All amino acids contain a carboxyl group and an
amino group. R-Groups distinguish between
individual amino acids. R-Groups make them
different from one another.
 Hydrogen
bonds are
weak electrical
attractions between
positively and
negatively charged
atoms of different
molecules.
 Covalent
bond between sulfur atoms on
two cysteine amino acids
 Ions
on R groups form
bridges through ionic
bonds
 Ionic bonds form from
the exchange of
electrons between
atoms
 Example: NaCl
(table salt)
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Close attraction of non-polar R
groups in the chains

Very weak but collective
interactions over large areas
help stabilize the protein
structure

The arrangement of many tertiary structures into one
large protein molecule

Not all proteins have or need a quaternary structure

Allows for changes in structure/function in response to
chemical stimuli