Basic HTML Version
62
linking glucose residues (from ADP-glucose) and by trimming chains.
Moreover, the chains are deposited in the granules in a highly ordered fashion
(see below).
1.5.2. Amyloses and amylopectins: Overview
Amylose
Amylopectin (AP)
Amount in starch
20-30%
70-80%
Structure
Essentially linear
α
-1,4
chains. Small amount of
short branches (5-21
branches per chain) in
10-70 % of the chains
Hyperbranched structure
based on
α
-1,4 linked
chains with
α
-1,6
branches.
Molecular size (native) M
w
in the range 10
5
-
10
6
M in the range 10
6
- 10
9
Phosphate monoester
Present in small amounts
(esp. in potato AP)
1.5.3. Amylose.
Amylose chains are mainly linear (unbranched) chains if
α
-1,4-linked glucose
residues:
Figure: Haworth formula of the amylose chain.
Each glucose residue is in the usual
4
C
1
conformation. Thus, O4 is in the
equatorial position, but O1 is axial:
O
CH
2
OH
OH
OH
O
O
CH
2
OH
OH
OH
O
O
CH
2
OH
OH
OH
O
CH
2
OH
O
OH
OH
O
O