Figure 4.

Kalihinol F is a copper chelator. a. BCA assay was performed on 5 mM CuCl₂ supplemented with EDTA, T-HCl, β-APN or kal F, in increasing molar excess. Copper chelation was determined by measuring absorbance at 562 nm. Graph shown above is representative of multiple experiments. b. Wild type W303 yeast cells were grown on YP-agar plate containing respiration-selective media treated with DMSO, BCS or kal F. Growth inhibition due to limiting copper levels was evaluated visually. Addition of copper, but not iron, was able to rescue yeast growth (lanes 3,4). Picture shown above is representative of multiple experiments. c. Effects of addition of Cu²⁺ to the ¹H NMR linewidths of H-5 (left panel) and the methyl group signals (right panel) of kalihinol F. d. Proposed binding site of copper based on previously determined x-ray structure of kalihinol F (Patra et al., 1984). Note that the isonitrile groups attached to C-5 and C-15 are oriented towards the same face of the molecule and potentially forms a bidentate coordination site for Cu²⁺ as depicted. Note also the proximity of H-5 and the furan ether group. See also Figure S3.