4ins

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spinqualitylabelsall models 4ins, resolution 1.5Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

THE STRUCTURE OF 2ZN PIG INSULIN CRYSTALS AT 1.5 ANGSTROMS RESOLUTION

Overview

The paper describes the arrangement of the atoms within rhombohedral, crystals of 2Zn pig insulin as seen in electron density maps calculated, from X-ray data extending to 1.5 A (1 A = 10(-10) m = 10(-1) nm) at room, temperature and refined to R = 0.153. The unit cell contains 2 zinc ions, 6 insulin molecules and about 3 x 283 water molecules. The atoms in the, protein molecules appear well defined, 7 of the 102 side chains in the, asymmetric unit have been assigned alternative disordered positions. The, electron density over the water molecules has been interpreted in terms of, 349 sites, 217 weighted 1.0, 126 weighted 0.5, 5 at 0.33 and 1 at 0.25, giving ca. 282 molecules. The positions and contacts of all the residues, belonging to the two A and B chains of the asymmetric unit are shown first, and then details of their arrangement in the two insulin molecules, 1 and, 2, which are different. The formation from these molecules of a compact, dimer and the further aggregation of three dimers to form a hexamer around, two zinc ions, follows. It appears that in the packing of the hexamers in, the crystal there are conflicting influences; too-close contacts between, histidine B5 residues in neighbouring hexamers are probably responsible, for movements of atoms at the beginning of the A chain of one of the two, molecules of the dimer that initiate movements in other parts, particularly near the end of the B chain. At every stage of the building, of the protein structure, residues to chains of definite conformation, molecules, dimers, hexamers and crystals, we can trace the effect of the, packing of like groups to like, aliphatic groups together, aromatic groups, together, hydrogen-bonded structures, positive and negative ions. Between, the protein molecules, the water is distributed in cavities and channels, that are continuous throughout the crystals. More than half the water, molecules appear directly hydrogen bonded to protein atoms. These are, generally in contact with other water molecules in chains and rings of, increasing disorder, corresponding with their movement through the, crystals. Within the established crystal structure we survey next the, distribution of hydrogen bonds within the protein molecules and between, water and protein and water and water; all but eight of the active atoms, in the protein form at least one hydrogen bond.(ABSTRACT TRUNCATED AT 400, WORDS)

About this Structure

4INS is a Protein complex structure of sequences from Sus scrofa with ZN as ligand. This structure superseeds the now removed PDB entry 1INS. The following page contains interesting information on the relation of 4INS with [Insulin]. Full crystallographic information is available from OCA.

Reference

The structure of 2Zn pig insulin crystals at 1.5 A resolution., Baker EN, Blundell TL, Cutfield JF, Cutfield SM, Dodson EJ, Dodson GG, Hodgkin DM, Hubbard RE, Isaacs NW, Reynolds CD, et al., Philos Trans R Soc Lond B Biol Sci. 1988 Jul 6;319(1195):369-456. PMID:2905485

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