ScienceAsia 24 (1998): 037-044 |doi: 10.2306/scienceasia1513-1874.1998.24.037

INTERACTIONS OF METHYL--CYCLODEXTRIN WITH ADENINE AND PYRIDINE/NICOTINAMIDE DERIVATIVES AS DETERMINED BY COMPETITIVE FLUORESCENCE METHODS

PIAMSOOK PONGSAWASDI^a,c AND BRUCE M. ANDERSON^b

ABSTRACT: In comparison with -cyclodextrin, methyl--cyclodextrin was more effective in binding TNS, as indicated by the higher fluorescence intensity enhancement and the higher association constant for the formation of the inclusion compound. Using a competitive fluorescence technique with the dye TNS, adenine and pyridine derivatives were observed to be relatively poor ligands, whereas, N¹-alkylnicotinamide chlorides formed inclusion compounds much more effectively with methyl--cyclodextrin. The effectiveness of binding of N¹-alkylnicotinamide chlorides increased as a function of the size of the alkyl substituent, with a positive chainlength effect being observed between the N¹-heptyl and N¹-dodecyl derivatives. The importance of nonpolar interactions in the binding of these derivatives was evident by the observed change in free energy per methylene unit of -0.548 kcal/mole.

Download PDF

a Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
b Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0308 U.S.A
c To whom correspondence should be addressed

Received November 30, 1997