Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
H2C H
H
H
A N C
O
H
O B
H
X X
0.35 nm
0.26 nm
0.55 nm
H O
O
H
O
O
H
H
O
H
H
H
H
B
O
O
O
H H
O H
H H
H O
O
X
(B)
H
H H
A
1'
1 3' 4'
2
5'
6
2'
5
6'
4 3
(AH)
FIGURE 5.3 AH,B,X Kier triangle sweetener. (a) In D-phenylalanine. (b) Typical dimensions.
(c) In sucrose.
If a sweet molecule is not planar, two configurations of AH,B,X are likely, of
which only one precisely fits the ah,b,x stereospecific receptor.
Subsequently, Shallenberger introduced the three-point AH,B,γ glycophore 6 in
which the γ point had a mixed lipophilic and hydrophobic character. In this theory,
dimension of a triangle is variable. The A-γ and B-γ distances for dipeptides are
higher than for the sweet α-amino acids.
5.5 B,AH,XH,G1–G4 HEPTAGONAL SWEETENER FOR
SACCHARIDES 7
Nofre and Tinti 7 formulated the multipoint attachment theory (MPA), which might
explain a binding of sweet ligands by the receptor in a transmembrane (TM) pocket.
A saccharide sweetener has seven interaction sites: B, AH, XH, G1, G2, G3, and
G4. Each site is composed of two interaction points, subsites (B1,B2), (AH1,AH2),
(XH1,XH2), (E1,G1), (E2,G2), (E3,G3) and (E4,G4), respectively. Figure 5.4 presents
the structure of this sweetener in the sweet-taste receptor pocket.
H
c)
A
a) b)
B