Basic HTML Version
15
Mannose is the 2-epimer of glucose (and
vice versa
)
Galactose is the 4-epimer of glucose (and
vice versa
)
(Remember these, they occur frequently in the course)
Anomers are epimers at the new asymmetric carbon formed after ring
formation. They are specifically given special symbols:
α
and
β
. The example
below illustrates the rules for both D- and L-sugars, and Fisher vs. Haworth.
O
CH
2
OH
HO
OH
OH
HOH
D-glucose
O
CH
2
OH
HO
OH
OH
HOH
D-mannose
O
CH
2
OH
OH
OH
OH
HOH
D-galactose
HOH: general notation - can be
α
or
β
C
C H
HO
C OH
H
C H
HO
C H
HO
CH
2
OH
O H
L-glucose
C
C H
HO
C OH
H
C H
HO
C H
CH
2
OH
H
HO
O
O
OH
OH
HO
CH
2
OH
OH
α
-L-glucose
C
C H
HO
C OH
H
C H
HO
C H
CH
2
OH
OH
H
O
O
OH
HO
CH
2
OH
OH
OH
β
-L-glucose
CYCLIC STRUCTURES: ANOMERS
L-sugars