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|Title:||Studies on the structure of the inclusion compound of β-cyclodextrin with aspartame|
|Authors:||Maheswaran, M M|
|Abstract:||Aspartame (N--aspartyl--phenylalanine-l-methyl ester, APM) forms an inclusion complex with β -cyclodextrin (BCD), with the phenylalanine ring present inside the hydrophobic cavity. A binding constant value of 211± 42 M-1 for the 1:1 complex has been determined. Detailed 1H NMR studies (chemical shift and ID NOE experiment) indicate that aspartame exists in the form of two conformers in DMSO-d6due to rotation around Cα -Cβ(Phe), NH - Cα,H(CH2Ph) and Cα - COOCH3. The proportions of these rotomers change on forming complex with BCD. The pK values of the COOH and NH2 groups of aspartic acid part of aspartame show small but observable changes due to complexation. NMR studies also indicate that the peptide backbone and the aspartyl portion bend over the edge of the BCD cavity involving hydrogen bonding of the 2-OH and 3-OH to the peptide NH - CO, bringing COOH close to the primary 6-OH group.|
|Appears in Collections:||IJC-A Vol.30A(01) [January 1991]|
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