Crystallographic titration of cubic insulin crystals: pH affects GluB13 switching and sulfate binding.Diao, J.
(2003) Acta Crystallogr.,Sect.D 59: 670-676
- PubMed: 12657786
- Primary Citation of Related Structures:
- Also Cited By: 1XW7
- PubMed Abstract:
- Water Structure in Cubic Insulin Crystals
Badger, J.,Caspar, D.L.
(1991) Proc.Natl.Acad.Sci.USA 88: 622
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(1978) J.Mol.Biol. 125: 387
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- Structure of the Pig Insulin Dimer in the Cubic Crystal
Badger, J.,Harris, M.R.,Reynolds, C.D.,Evans, A.C.,Dodson, E.J.,Dodson, G.G.,North, A.C.T.
(1991) Acta Crystallogr.,Sect.B 47: 127
Structures of porcine insulin crystals soaked in 1 M sodium sulfate at pH 5.00, 5.53, 5.80, 6.00, 6.16, 6.26, 6.35, 6.50, 6.98 and 9.00 have been determined at between 1.7 and 1.9 A resolution. GluB13 exhibits a single conformation at pH </= 5.80, tw ...
Structures of porcine insulin crystals soaked in 1 M sodium sulfate at pH 5.00, 5.53, 5.80, 6.00, 6.16, 6.26, 6.35, 6.50, 6.98 and 9.00 have been determined at between 1.7 and 1.9 A resolution. GluB13 exhibits a single conformation at pH = 5.80, two conformations between pH 6.00 and 6.98 and a single conformation at pH 9.00. Between pH 6.00 and 6.98, the conformation of GluB13 switches from one rotamer to another rotamer. Between pH 6.16 and 6.26, PheB1 undergoes a significant conformational change. By pH 9.00 many residues have undergone relatively large shifts and HisB10 exhibits a double conformation. As a result of the pH increase, the occupancy of the sulfate ion decreases from a maximum of 1.00 at pH 5.00 to a minimum of 0.46 at pH 6.50. Comparison of the structures, the observed and calculated structure factors and map correlation coefficients indicate that the porcine insulin structure changes gradually as a function of pH.
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