3INS

STRUCTURE OF INSULIN. RESULTS OF JOINT NEUTRON AND X-RAY REFINEMENT

Summary for 3INS

• Entry DOI: 10.2210/pdb3ins/pdb
• Descriptor: INSULIN (CHAIN A), INSULIN (CHAIN B), ZINC ION, ... (4 entities in total)
• Functional Keywords: hormone
• Biological source: Sus scrofa (pig); More
• Cellular location: Secreted: P01315 P01315
• Total number of polymer chains: 4
• Total formula weight: 11706.07

Authors

Wlodawer, A.,Savage, H. (deposition date: 1988-10-14, release date: 1989-01-09, Last modification date: 2024-11-06)

Primary citation

Wlodawer, A.,Savage, H.,Dodson, G.
Structure of insulin: results of joint neutron and X-ray refinement.
Acta Crystallogr.,Sect.B, 45:99-107, 1989

PubMed Abstract: Neutron diffraction data for porcine 2Zn insulin were collected to 2.2 A resolution from a single crystal deuterated by slow exchange of mother liquor. A joint neutron/X-ray restrained-least-squares refinement was undertaken using the neutron data, as well as the 1.5 A resolution X-ray data collected previously. The final R factors were 0.182 for the X-ray data and 0.191 for the neutron data. Resulting atomic coordinates were compared with the initial X-ray model, showing a total r.m.s. shift of 0.36 A for the protein and 0.6 A for the solvent. Protonation of a number of individual amino acids was investigated by analysis of the neutron maps. No D atoms were found between the carboxylates of Glu B13 which make an intermolecular contact, suggesting nonbonded interaction rather than the predicted hydrogen bond. Amide hydrogen exchange was investigated in a refinement of their atomic occupancies. Regions of unexchanged amide groups were found in the center of the B helices. The results of this study emphasize the limited amount of information available in neutron diffraction studies of proteins at resolution lower than 2 A.

PubMed: 2695122
DOI: 10.1107/S0108768188011012

Experimental method

NEUTRON DIFFRACTION (2.2 Å)
X-RAY DIFFRACTION (1.5 Å)