RT Journal Article
SR Electronic
T1 Induced Conformational Changes in Novobiocin
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 751
OP 758
VO 8
IS 6
A1 JOSEPH G. BRAND
A1 T. Y. TORIBARA
YR 1972
UL http://molpharm.aspetjournals.org/content/8/6/751.abstract
AB The techniques of ultraviolet absorption spectroscopy and circular dichroism have been utilized to demonstrate in the substituted coumarin antibiotic, novobiocin sodium, a conformational change which could be induced by making the solution acidic. By comparing the ultraviolet spectra of novobiocin with those of coumarin and warfarin, a less complex substituted coumarin, the region of interest in the spectrum has been assigned to transitions within the coumarin ring. Upon acidification a large bathochromic shift was observed only for novobiocin, and has been attributed to increased conjugation as a result of an alignment of the benzamido group attached to position 3 of the coumarin skeleton of the drug. Also upon acidification, an inversion in sign of the circular dichroic band has been noted and has been attributed to a movement of the perturbing benzyl group to a negatively rotating quadrant in accordance with the octant rule. The entirely different circular dichroic spectra of the human albumin-novobiocin complex and the bovine albumin-novobiocin complex may be explained in terms of different conformational changes induced in the novobiocin molecule upon being bound to the two proteins.