Chemical and thermal stability of insulin: effects of zinc and ligand binding to the insulin zinc-hexamer.

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Huus K, Havelund S, Olsen HB, van de Weert M, Frokjaer S

Chemical and thermal stability of insulin: effects of zinc and ligand binding to the insulin zinc-hexamer.

Pharm Res. 2006 Nov;23(11):2611-20. Epub 2006 Sep 13.

PubMed ID

16969698 [ View in PubMed

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Abstract

PURPOSE: To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands. MATERIALS AND METHODS: The thermal stability was investigated using differential scanning calorimetry (DSC) and near-UV circular dichroism (NUV-CD). The formation of chemical degradation products was studied with reversed-phase and size-exclusion chromatography and mass spectrometry. RESULTS: An excellent correlation between the thermal stabilization by ligand binding and the deamidation of Asn(B3) was observed. The correlation between thermal stability and the formation of covalent dimer and other insulin related products was less clear. Zinc was found to specifically increase the deamidation and covalent dimer formation rate when the insulin hexamer was not further stabilized by phenolic ligand. Thiocyanate alone had no effect on the thermal stability of the insulin zinc-hexamer but significantly improved the chemical stability at 37 degrees C. At low temperatures thiocyanate induced a conformational change in the insulin hexamer. NUV-CD thermal scans revealed that this effect decreased with temperature; when the thermal denaturation temperature was reached, the effect was eliminated. CONCLUSIONS: Thermal stability can be used to predict the rate of Asn(B3) deamidation in human insulin. Chemical degradation processes that do not rely on the structural stability of the protein do not necessarily correlate to the thermal stability.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Zinc	Insulin	Protein	Humans	Unknown	Not Available	Details
Zinc acetate	Insulin	Protein	Humans	Unknown	Not Available	Details
Zinc chloride	Insulin	Protein	Humans	Unknown	Stabilization	Details
Zinc sulfate, unspecified form	Insulin	Protein	Humans	Unknown	Stabilization	Details