Supramolecular protein engineering: design of zinc-stapled insulin hexamers as a long acting depot.
Bottom-up control of supramolecular protein assembly can provide a therapeutic nanobiotechnology. We demonstrate that the pharmacological properties of insulin can be enhanced by design of "zinc staples" between hexamers. Paired (i, i+4) His substitutions were introduced at an alpha-helical surface. The crystal structure contains both classical axial zinc ions and novel zinc ions at hexamer-hexamer interfaces. Although soluble at pH 4, the combined electrostatic effects of the substitutions and bridging zinc ions cause isoelectric precipitation at neutral pH. Following subcutaneous injection in a diabetic rat, the analog effected glycemic control with a time course similar to that of long acting formulation Lantus. Relative to Lantus, however, the analog discriminates at least 30-fold more stringently between the insulin receptor and mitogenic insulin-like growth factor receptor. Because aberrant mitogenic signaling may be associated with elevated cancer risk, such enhanced specificity may improve safety. Zinc stapling provides a general strategy to modify the pharmacokinetic and biological properties of a subcutaneous protein depot.
Phillips
Nelson B
NB
Department of Biochemistry, Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.
Wan
Zhu-li
ZL
Whittaker
Linda
L
Hu
Shi-Quan
SQ
Huang
Kun
K
Hua
Qing-xin
QX
Whittaker
Jonathan
J
Ismail-Beigi
Faramarz
F
Weiss
Michael A
MA
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003692:Delayed-Action Preparations; D015195:Drug Design; D006801:Humans; D007328:Insulin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D015202:Protein Engineering / Q000379:methods; D017433:Protein Structure, Secondary; D051381:Rats; D055672:Static Electricity; D015032:Zinc / Q000737:chemistry
D003692:Delayed-Action Preparations; D007328:Insulin; D015032:Zinc