Investigation of a CuII–Poly(γ-Glutamic Acid) Complex in Aqueous Solution and its Insulin-Mimetic Activity

✍ Scribed by Subarna Karmaker; Tapan K. Saha; Hiromu Sakurai

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 282 KB
• Volume: 7
• Category: Article
• ISSN: 1616-5187
• DOI: 10.1002/mabi.200600227

✦ Synopsis

Abstract

The complexation between cupric ions (Cu^II^) and poly(γ‐glutamic acid) (γ‐PGA) in aqueous solutions (pH 3–11) has been studied by UV‐visible absorption and electron spin resonance (ESR) techniques. Formation of the Cu^II^‐γ‐PGA complex is confirmed by the observation of the blue shift of the absorption band in the visible region, anisotropic line shapes in the ESR spectrum at room temperature, and a computer simulation of the visible absorption spectrum of the complex. The structure of the Cu^II^‐γ‐PGA complex, depending on the pH, has been determined. The in vitro insulin‐mimetic activity of the Cu^II^‐γ‐PGA complex is examined by determining both inhibition of free fatty acid release and glucose uptake in isolated rat adipocytes treated with epinephrine, in which the concentration of the Cu^II^‐γ‐PGA complex for 50% inhibition of free fatty acid release is very similar to that of CuSO~4~. However, it is significantly lower than that of a previously reported insulin‐mimetic bis(3‐hydroxypicolinato)copper(II), [Cu(3hpic)~2~], complex.

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