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Recombinant human insulin does not dissolve in chloroform. Insulin is inherently a water-soluble protein due to its amino acid composition, favoring polar interactions. Chloroform, being a non-polar solvent, is incompatible with the hydrophilic nature of insulin, resulting in its insolubility. Studies show that insulin's solubility is influenced by pH and specific additives in aqueous solutions, but not by non-polar solvents like chloroform [1][2][4][5]. Even modifications to enhance insulin's solubility in non-aqueous solvents, such as complex formation with detergents, do not extend to chloroform [3]. Therefore, chloroform remains unsuitable for dissolving recombinant human insulin.

Reference

[1] Landreh, M., Alvélius, G., Willander, H., Stukenborg, J., Söder, O., Johansson, J., & Jörnvall, H. (2012). Insulin solubility transitions by pH‐dependent interactions with proinsulin C‐peptide. The FEBS Journal, 279.

[2] Matsuura, J., Powers, M. E., Manning, M., & Shefter, E. (1993). Structure and stability of insulin dissolved in 1-octanol. Journal of the American Chemical Society, 115, 1261-1264.

[3] Quinn, R., & Andrade, J. (1983). Minimizing the aggregation of neutral insulin solutions.. Journal of pharmaceutical sciences, 72 12, 1472-3 .

[4] Selam, J., Zirinis, P., Mellet, M., & Mirouze, J. (1987). Stable Insulin for Implantable Delivery Systems: In Vitro Studies With Different Containers and Solvents. Diabetes Care, 10, 343 - 347.

[5] Lee, S., Kim, K., Kumar, T. S., Lee, J., Kim, S., Lee, D. Y., Lee, Y., & Byun, Y. (2005). Synthesis and biological properties of insulin-deoxycholic acid chemical conjugates.. Bioconjugate chemistry, 16 3, 615-20 .