Crystallographic and solution studies of N-lithocholyl insulin: A new generation of prolonged-acting human insulins

TY - JOUR

T1 - Crystallographic and solution studies of N-lithocholyl insulin

T2 - A new generation of prolonged-acting human insulins

AU - Whittingham, J L

AU - Jonassen, I

AU - Havelund, S

AU - Roberts, S M

AU - Dodson, E J

AU - Verma, C S

AU - Wilkinson, A J

AU - Dodson, G G

PY - 2004/5/25

Y1 - 2004/5/25

N2 - The addition of specific bulky hydrophobic groups to the insulin molecule provides it with affinity for circulating serum albumin and enables it to form soluble macromolecular complexes at the site of subcutaneous injection, thereby securing slow absorption of the insulin analogue into the blood stream and prolonging its half-life once there. N-Lithocholic acid acylated insulin [Lys(B29)-lithocholyl des-(B30) human insulin] has been crystallized and the structure determined by X-ray crystallography at 1.6 A resolution to explore the molecular basis of its assembly. The unit cell in the crystal consists of an insulin hexamer containing two zinc ions, with two m-cresol molecules bound at each dimer-dimer interface stabilizing an R-6 conformation. Six covalently bound lithocholyl groups are arranged symmetrically around the outside of the hexamer. These form specific van der Waals and hydrogen-bonding interactions at the interfaces between neighboring hexamers, possibly representing the kinds of interactions which occur in the soluble aggregates at the site of injection. Comparison with an equivalent nonderivatized native insulin hexamer shows that the addition of the lithocholyl group disrupts neither the important conformational features of the insulin molecule nor its hexamer-forming ability. Indeed, binding studies show that the affinity of N-lithocholyl insulin for the human insulin receptor is not significantly diminished.

AB - The addition of specific bulky hydrophobic groups to the insulin molecule provides it with affinity for circulating serum albumin and enables it to form soluble macromolecular complexes at the site of subcutaneous injection, thereby securing slow absorption of the insulin analogue into the blood stream and prolonging its half-life once there. N-Lithocholic acid acylated insulin [Lys(B29)-lithocholyl des-(B30) human insulin] has been crystallized and the structure determined by X-ray crystallography at 1.6 A resolution to explore the molecular basis of its assembly. The unit cell in the crystal consists of an insulin hexamer containing two zinc ions, with two m-cresol molecules bound at each dimer-dimer interface stabilizing an R-6 conformation. Six covalently bound lithocholyl groups are arranged symmetrically around the outside of the hexamer. These form specific van der Waals and hydrogen-bonding interactions at the interfaces between neighboring hexamers, possibly representing the kinds of interactions which occur in the soluble aggregates at the site of injection. Comparison with an equivalent nonderivatized native insulin hexamer shows that the addition of the lithocholyl group disrupts neither the important conformational features of the insulin molecule nor its hexamer-forming ability. Indeed, binding studies show that the affinity of N-lithocholyl insulin for the human insulin receptor is not significantly diminished.

KW - ASSOCIATION PROPERTIES

KW - ALBUMIN-BINDING

KW - NPH INSULIN

KW - M-CRESOL

KW - PHENOL

KW - HEXAMER

KW - ACIDS

KW - REPLACEMENT

KW - REFINEMENT

KW - DETEMIR

U2 - 10.1021/bi036163s

DO - 10.1021/bi036163s

M3 - Article

SN - 0006-2960

VL - 43

SP - 5987

EP - 5995

JO - Biochemistry

JF - Biochemistry

IS - 20

ER -