My dad and I with Insulin molecule.
Insulin protein hormone. "Insulin is a hormone that is central to regulating energy and glucose metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle." (http://en.wikipedia.org/wiki/Insulin)
This model is a molecular surface of the A chain and the B chain of the asymmetric unit for PDB: 1trz from http://www.pdb.org/pdb/explore/explore.do?structureId=1TRZ.
The model is presented 10 million time larger than real life. That means that the physical model's 2.8 centimeters in height actually represent 28 Angstroms in the cell.
Crystallographic evidence for dual coordination around zinc in the T3R3 human insulin hexamer.
Ciszak, E., Smith, G.D.
Journal: (1994) Biochemistry 33: 1512-1517
PubMed: 8312271 View PubMed Abstract at NCBI
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The T3R3 human insulin hexamer (T and R referring to extended and alpha-helical conformations, respectively, of the first eight residues of the B-chain), complexed to two zinc ions, crystallizes in space group R3 with hexagonal cell constants a = 80.64... [ Read More & Search PubMed Abstracts ]
The T3R3 human insulin hexamer (T and R referring to extended and alpha-helical conformations, respectively, of the first eight residues of the B-chain), complexed to two zinc ions, crystallizes in space group R3 with hexagonal cell constants a = 80.64 and c = 37.78 A. The structure has been refined to a residual of 0.172 using 9225 independent data to 1.6-A resolution. The asymmetric unit consists of a TR dimer, and the insulin hexamer is generated by the action of the crystallographic 3-fold axis. The conformation of one insulin trimer is nearly identical to that of the T6 hexamer, while the other trimer approximates that of the R6 hexamer, except for the three N-terminal B-chain residues that adopt an extended rather than an alpha-helical conformation. Each of the two zinc ions, which lie on the crystallographic 3-fold axis and exhibit two different, disordered coordination geometries, is coordinated by the imidazole groups of three symmetry-related B10 histidine residues. The coordination sphere of the zinc in the T3 trimer is either tetrahedral, with the fourth site filled by a chloride ion, or octahedral, completed by three water molecules. The coordination of the zinc in the 12-A narrow channel in the R3 trimer is tetrahedral, with either a second chloride ion or a water molecule completing the coordination sphere. The putative off-axial zinc binding sites that result from the T-->R transition of monomer II do not contain zinc ion, but instead are filled with clusters of ordered water molecules.(ABSTRACT TRUNCATED AT 250 WORDS)
NOTE: This is just one-sixth of the hexamer!!
Binding Sites, Crystallization, Crystallography, X-Ray, Humans, Hydrogen Bonding, Insulin, Macromolecular Substances, Molecular Structure, Protein Conformation, Protein Structure, Secondary, Zinc