PDBsum entry 1b2a

Hormone/growth factor

PDB id: 1b2a

Contents

Protein chains

21 a.a.

30 a.a. *

Ligands

SO4

Waters ×66

* Residue conservation analysis

PDB id:

1b2a

Name:

Hormone/growth factor

Title:

Ph affects glu b13 switching and sulfate binding in cubic insulin crystals (ph 6.00 coordinates)

Structure:

Protein (insulin a chain). Chain: a. Protein (insulin b chain). Chain: b

Source:

Sus scrofa. Pig. Organism_taxid: 9823. Organ: pancreas. Organ: pancreas

Biol. unit:

Dimer (from PQS)

Resolution:

1.70Å R-factor: 0.188 R-free: 0.230

Authors:

J.S.Diao,D.L.D.Caspar

Key ref:

J.Diao (2003). Crystallographic titration of cubic insulin crystals: pH affects GluB13 switching and sulfate binding. Acta Crystallogr D Biol Crystallogr, 59, 670-676. PubMed id: 12657786 DOI: 10.1107/S0907444903002208

Date:

26-Nov-98 Release date: 08-Apr-03

Protein chain

P01315  (INS_PIG) -  Insulin from Sus scrofa

Seq: 108 a.a.

Struc: 21 a.a.

Protein chain

P01315  (INS_PIG) -  Insulin from Sus scrofa

Seq: 108 a.a.

Struc: 30 a.a.

DOI no: 10.1107/S0907444903002208

Acta Crystallogr D Biol Crystallogr 59:670-676 (2003)

PubMed id: 12657786

Crystallographic titration of cubic insulin crystals: pH affects GluB13 switching and sulfate binding.

J.Diao.

ABSTRACT

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.

Selected figure(s)

Figure 2.
Figure 2 Structures at ten different pH and corresponding 2F[o] - F[c] maps. Structures in the region of GluB13 and the sulfate ion are presented and 2F[o] - F[c] maps are contoured at the 0.8 level because of the approximate half-occupancy of the two rotamers of GluB13 and the lower electron density compared with the rest of the structure. Sub-figures correspond to the structures at pH 5.00, 5.53, 5.80, 6.00, 6.16, 6.26, 6.35, 6.50, 6.98 and 9.00, respectively.

Figure 4.
Figure 4 Sulfate-binding region. The coordinates at pH 5.00 were used to produce the figure.

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (2003, 59, 670-676) copyright 2003.

Figures were selected by an automated process.