7QAC

The T2 structure of polycrystalline cubic human insulin

Summary for 7QAC

• Entry DOI: 10.2210/pdb7qac/pdb
• Descriptor: Insulin A chain, Insulin B chain (3 entities in total)
• Functional Keywords: cubic, human, insulin, t2, hormone
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 2
• Total formula weight: 5817.65

Authors

Karavassili, F.,Triandafillidis, D.P.,Valmas, A.,Spiliopoulou, M.,Fili, S.,Kontou, P.,Bowler, M.W.,Von Dreele, R.B.,Fitch, A.,Margiolaki, I. (deposition date: 2021-11-16, release date: 2023-06-21, Last modification date: 2024-10-09)

Primary citation

Triandafillidis, D.P.,Karavassili, F.,Spiliopoulou, M.,Valmas, A.,Athanasiadou, M.,Nikolaras, G.,Fili, S.,Kontou, P.,Bowler, M.W.,Chasapis, C.T.,Von Dreele, R.B.,Fitch, A.N.,Margiolaki, I.
The T 2 structure of polycrystalline cubic human insulin.
Acta Crystallogr D Struct Biol, 79:374-386, 2023

PubMed Abstract: The polymorphism of human insulin upon pH variation was characterized via X-ray powder diffraction, employing a crystallization protocol previously established for co-crystallization with phenolic derivatives. Two distinct rhombohedral (R3) polymorphs and one cubic (I23) polymorph were identified with increasing pH, corresponding to the T, TR and T conformations of insulin, respectively. The structure of the cubic T polymorph was determined via multi-profile stereochemically restrained Rietveld refinement at 2.7 Å resolution. This constitutes the first cubic insulin structure to be determined from crystals grown in the presence of zinc ions, although no zinc binding was observed. The differences of the polycrystalline variant from other cubic insulin structures, as well as the nature of the pH-driven phase transitions, are discussed in detail.

PubMed: 37039669
DOI: 10.1107/S2059798323001328

Experimental method

POWDER DIFFRACTION (2.29 Å)