7. 1. Conversion of β-D-galactose to α-Dgalactose
2. Phosphorylation on C1 with ATP and
galactokinase
ATP + D galactose ----->
D galactose-1-phosphate+ ADP + H
8.
9.
10. Ribbon representation of
galactose mutarotase from L.
lactis.
The two subunits of the
dimeric protein are displayed
in red and blue. Bound
galactose molecules are
depicted in ball-and-stick
representations. X-ray
coordinates were from Protein
Data Bank number 1L7K.
11. Cartoon diagram of a human
galactokinase 1 monomer in
complex with galactose (red)
and an analogue of
adenosine triphosphate
(orange).
A magnesium ion is visible as
a green sphere.
12. 3. Conversion of galactose-1phosphate into glucose-1-phosphate
by galactose-1-phosphate
uridyltransferase
13.
14. Ribbon representation of
galactose-1-phosphate
uridylyltransferase from E.
coli.
The two subunits of the
dimeric enzyme are
displayed in red and blue
with the positions of the
metals indicated by the
round spheres. The active
site in this protein model
contains bound UDPglucose. X-ray coordinates
were from Protein Data
Bank number 1GUQ.
15. Recycle of the UDP-galactose to UDPglucose for the transferase reaction.
16. Ribbon representation of human
UDP-galactose 4-epimerase.
Each subunit of the dimeric enzyme
folds into two domains. The N- and Cterminal domains are color-coded in
blue and red, respectively. Bound
NADH and UDP-glucose molecules
are drawn in ball-and-stick
representations. X-ray coordinates
were from Protein Data Bank number
1EK6.
