Molecular recognition of alpha-cyclodextrin (CD) to choral amino acids based on methyl orange as a molecular probe.
The molecular recognition interaction of alpha-CD to chiral amino acids was investigated by using spectrophotometry based on methyl orange as a molecular probe. The molecular recognition ability depended on the inclusion formation constants. The molecular recognition of alpha-CD to aromatic amino acids was the order: DL-tryptophan > L-tryptophan > L-phenylalanine > L-tyrosine approximately DL-beta-3,4-dihydroxy-phenylalanine; whereas for aliphatic amino acids, the order was: L-iso-leucine > L-leucine approximately L-methionine approximately DL-mehtionine > D-leucine. The effect of temperature on the inclusion interaction was examined and the thermodynamic parameters of inclusion process, delta G, delta H, delta S, were determined. The experimental results indicated that the inclusion process was an exothermic and enthalpy-driven process accompanied with a negative or minor positive entropic contribution. The inclusion interaction between alpha-CD and amino acids satisfied the law of enthalpy-entropy compensation. The compensation temperature was 291 K.
Yuexian
Fan
F
College of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, PR China.
Yu
Yang
Y
Shaomin
Shuang
S
Chuan
Dong
D
D024322:Amino Acids, Aromatic / Q000378:metabolism*; D001391:Azo Compounds; D015335:Molecular Probes; D013816:Thermodynamics; D047391:alpha-Cyclodextrins / Q000378:metabolism*
D024322:Amino Acids, Aromatic; D001391:Azo Compounds; D015335:Molecular Probes; D047391:alpha-Cyclodextrins; C100258:methyl orange; C032613:alpha-cyclodextrin