Insulin analog with additional disulfide bond has increased stability and preserved activity

Area of Science:

• Biochemistry
• Endocrinology
• Protein Engineering

Background:

• Insulin is crucial for glucose homeostasis, with a conserved structure featuring three disulfide bonds essential for function.
• Enhanced structural stability is desirable for pharmaceutical insulin applications.

Purpose of the Study:

• To investigate if an additional disulfide bond can improve insulin's structural stability and pharmaceutical properties.
• To design and characterize a novel insulin analog with a fourth disulfide bond.

Main Methods:

• Designed an insulin analog with an additional interchain disulfide bond at positions A10/B4.
• Assessed insulin receptor binding affinity and glucodynamic potency in a rat model.
• Determined melting temperature, evaluated fibril formation under stress, and analyzed crystal structure.

Main Results:

• The novel analog exhibited increased insulin receptor affinity and augmented glucodynamic potency.
• A 34.6°C increase in melting temperature and prevention of insulin fibril formation were observed.
• The analog retained hexamer formation capability and showed minor structural deviations from human insulin.

Conclusions:

• The first insulin analog with a fourth disulfide bond demonstrates enhanced structural stability and retained function.
• This engineered insulin shows promise for pharmaceutical development due to improved stability and potency.
• The study suggests the R-state conformation is not essential for insulin receptor binding.