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Chiral recognition of dipeptide methyl esters by an anionic β‐cyclodextrin
Author(s) -
Kano Koji,
Hasegawa Hideki,
Miyamura Muneki
Publication year - 2001
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.1064
Subject(s) - chemistry , dipeptide , enantiomer , stereochemistry , chirality (physics) , nuclear magnetic resonance spectroscopy , protonation , amino acid , residue (chemistry) , molecular recognition , organic chemistry , molecule , biochemistry , ion , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
Chiral recognition of dipeptide methyl esters by anionic heptakis[6‐carboxymethylthio‐6‐deoxy]‐β‐cyclodextrin (per‐CO 2 − ‐β‐CD) was studied in D 2 O at pD 7.0 by means of 1 H NMR spectroscopy. The methyl esters of alanylalanine (Ala‐Ala‐OMe), alanylleucine (Ala‐Leu‐OMe), alanyltryptophan (Ala‐Trp‐OMe), glycyltryptophan (Gly‐Trp‐OMe), valyltryptophan (Val‐Trp‐OMe), leucyltryptophan (Leu‐Trp‐OMe), and tryptophylalanine (Trp‐Ala‐OMe) were used as the dipeptides. The binding constant ( K ) determined from NMR titration increases in the order Ala‐Ala‐OMe < Ala‐Leu‐OMe < Ala‐Trp‐OMe, suggesting that van der Waals interactions between the host and the guest participate in complexation. Coulomb interactions between the protonated dipeptide methyl esters and the anionic host seem to be another attractive force. Per‐CO 2 − ‐β‐CD interacts with the ( R,R )‐enantiomers of the dipeptide methyl esters more strongly than the ( S,S )‐enantiomers. Such enantioselectivity corresponds to that for α‐amino acid methyl esters such as Leu‐OMe and Trp‐OMe, whose ( R )‐enantiomers are the preferable guests. The enantioselectivity is mainly dominated by amino acid residue at the C ‐terminal and chirality at the N ‐terminal residue plays an assistant role. An asymmetrically twisted shape of the host cavity may be essential for chiral recognition. Chirality 13:474–482, 2001. © 2001 Wiley‐Liss, Inc.