Short-term insulin-induced glycogen formation in primary hepatocytes as a screening bioassay for insulin action

Ethylenediamine-assisted preparation of carbon nanofiber supported nickel oxide electrocatalysts for sensitive and durable detection of insulin

Facile preparation of a carbon nanofibers/nickel oxide nanocomposite and its sensitive and durable performance for insulin electrocatalytic oxidation.

Electrochemical study of insulin at the polarized liquid-liquid interface

This paper reports on the electrochemical behavior of bovine insulin at the interface between two immiscible electrolyte solutions (ITIES). The voltammetric ion-transfer response obtained in the presence of insulin was dependent on the aqueous phase pH conditions and on the nature of the organic phase electrolyte employed in experiments. Optimal detection was obtained at acidic pH below the isoelectric point of insulin where it was positively charged. A shift in transfer potentials to lower potential values was observed with decreasing hydrophobicity of the anion of the organic phase electrolyte. No ion-transfer response was observed at pH values of the aqueous phase above the isoelectric point, where insulin was negatively charged. These results suggest that the voltammetric response is due to ion-pairing interactions at the ITIES between positively charged insulin and the hydrophobic anion of the organic phase electrolyte, together with adsorption of the ion-pair at the interface. The voltammetric response was obtained for insulin at concentrations down to 1 muM. These results show that electrochemistry is useful in studying the behavior of this important protein molecule at the polarized water-1,2-DCE interface and provides an alternative detection mode for bioanalytical applications.

Synthesis, and functional properties of a modified human insulin A-chain: implication in a 'mini-insulin' structure determination

The design and total synthesis of a novel insulin A-chain mutant, analogue 3, is reported. In this compound, the cysteines implied in the two insulin inter-chain disulfide bridges are replaced by two serines (residues Ser(A7) and Ser(A20)) and the intra-A-chain disulfide bridge (residues Cys(A6) and Cys(A11)) is conserved. This A-chain analogue (3) has been tested in three in vitro cell culture assays, using insulin as a reference. The data clearly showed that analogue 3 mimics insulin effects on DNA synthesis, glucose uptake and glycogen synthesis without loss of potency as compared to insulin. To our knowledge, these are the first results showing that an isolated insulin chain displays functional properties similar to those of insulin. The implication of these new findings in insulin structure-function relationships and in a 'mini-insulin' structure determination is discussed.