Levels of protein structure shown by the Insulin molecule
Amino acid colour codes:
ASP, GLU,
CYS, MET,
LYS, ARG,
SER, THR,
PHE, TYR,
ASN, GLN,
GLY,
LEU, VAL, ILE ,
ALA,
TRP,
HIS and
PRO.
PRIMARY STRUCTURE
- amino acid sequence
The insulin molecule consists of 51 amino acid residues, in two chains.
Initial scheme shows 764 atoms (ball and stick), coloured by elements.
Highlight peptide bonds (-CONH-) between amino acids.
Show individual amino acids (coloured according to codes above):
ball and stick
/ simple trace format.
Name /
number /
unlabel A chain residues
Name /
number /
unlabel B chain residues
- association (involving non-covalent bonds) of more than one polypeptide chain subunits to form a functional protein
The two-chain structure of insulin is not usually seen as the quaternary level since it is stabilised by disulphide bonds (and both chains came from a single polypeptide originally).
However, in the presence of mineral ions, insulin may associate to form dimers, tetramers etc. Zinc ions cause insulin to form into a stable hexamer (6 A & B chains). This hexameric form is found in beta-cells of the islets of Langerhans, and it is seen as helpful in prolonging the usefulness of insulin in treating diabetes. Show hexameric form ... show zinc
This graphics display was prepared to support a unit on the levels of protein structure using insulin as an example with several static graphics.