Long chain fatty acid and ketone arise albumin structure recovery caused by furosemide.

Applied various spectroscopic techniques, such as fluorescence spectroscopy and circular dichroism, etc., the interaction between furosemide (FU) and bovine serum albumin (BSA), as well as the effects of long-chain fatty acid and ketone on the conformational changes of BSA induced by furosemide were studied. The results showed that furosemide strongly quenched the endogenous fluorescence of BSA. Fatty acid sites 7, 6, and/or 1 were the high affinity sites of FU, while its low affinity sites were not in the vicinity of the seven binding sites of oleic acid. When FU binds to high affinity sites, it can cause decrease of the percentage of α-helices, while binding to its low affinity sites leads to tertiary structural change. The binding of FU induces a significant red shift in the maximum fluorescence wavelength, indicating that it triggers a change in the tertiary structure. Long chain fatty acids and ketones have a restorative effect on the tertiary structural changes of BSA induced by FU in different mechanisms and this recovery does not originate from the alteration of the percentage of α-helices.