L31 462a_carb1_lec31_2012

Commondisaccharides polysaccharidesglycans branching

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Unformatted text preview: as
stereoisomers.
Your
body
can
tell
the
difference
 •  Nice
site
to
check
out
stereochemistry
of
carbohydrates:
 –  hep://www.elmhurst.edu/~chm/vchembook/542isomers.html
 EnanDomers:
mirror
images
 •  Different
representaDons
of
D
&
L‐glyceraldehyde
 enanDomers
 Lehninger
Fiah
ediDon,
Figure
7‐2
 Epimers
 •  Two
sugars
that
differ
in
configuraDon
around
 a
single
carbon
 Lehninger
Fiah
ediDon,
Figure
7‐4
 CyclizaDon
of
Monosaccharides
 Monosaccharides
react
intra‐molecularly
to
become
cyclic
 ReacDon
of
CyclizaDon
 •  CyclizaDon
is
an
example
of
a
more
general
reacDon
of
 an
alcohol
(‐OH)
with
an
aldehyde
or
ketone
(C=O).
 •  Nucleophilic
aeack
on
the
carbonyl
carbon
by
a
 hydroxyl
group.
 •  ReacDon
is
freely
reversible.

 2
Common
 Rings
 Sugars
with
5
or
more
 C
atoms
can
form
 • 
5‐membered
 

furanose rings
 










or
 • 
6‐membered
 


pyranose rings.
 Anomers
 •  By
cyclizaDon,
carbonyl
C
becomes
a
new
chiral
center
–
 anomeric carbon •  2
different
isomers
can
be
formed
–
α
and
β anomers •  Inter...
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This note was uploaded on 01/22/2014 for the course BIOC 462A taught by Professor Ziegler,baldwin during the Winter '08 term at University of Arizona- Tucson.

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