Biomedical Engineering Reference
In-Depth Information
In ring structure, ketopentoses look similar to ribofuranose (
D
-ribulose) and xylofuranose
(
D
-xylose), except the hydroxyl group next to the ester O.
HO
CH
2
OH
C
HCOH
HCOH
H
2
C
CH
2
OH
C
HOCH
HCOH
H
2
C
O
HO
HO
OH
O
O
HO
OH
β
-
D
-xylulose
D
-ribulose
D
-xylulose
c.
Ketotetroses
CH
2
OH
CO
HCOH
CH
2
OH
D
-erythrulose
d.
Ketotriose
There is only one common ketotriose in nature, that is,
CH
2
OH
CO
CH
2
OH
or Dihydroxyacetone.
2.3.2.1.3. DEOXYSUGARS
Deoxysugars are the sugars shown above with one or more oxygen atoms removed
from the hydroxyl groups. Three commonly seen deoxysugars are
L
-rhamnose (deoxy
mannose or methyl lyxose),
L
-fucose (deoxy galactose or methyl arabinose), and
D
-deoxy-
ribose. Both rhamnose
and fucose
are deoxyhexoses, while deoxyribose
is
adeoxypentose.
HO
OH
OH
O
O
O
HO
HO
OH
OH
OH
OH
OH
OH
β
-
L
-fucose
α
-
D
-deoxyribose
α
-
L
-rhamnose
Particularly important monosaccharides are
D
-ribose and deoxyribose. These five carbon
ring-structured sugar molecules are essential components of DNA and RNA.
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