Niacin Vitamin B3

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THIAMIN (VITAMIN B1)
4-Methyl-5-hydroxyethyl-thiazole
2,5-Dimethyl-6-aminopyrimidine
Methylene bridge
????? http//www.indstate.edu/thcme/mwking/vitam
ins.html
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Coenzyme Form ??? Thiamin
Thiamin pyrophosphate (active form)
????? http//www.indstate.edu/thcme/mwking/vitam
ins.html
reactive group
????? Lehninger et al, 1993
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Thiamin
ATP - dependent thiamin pyrophosphotransferase (
brain, liver )
Thiamin pyrophosphate (TPP)

• ???? coenzyme ??? enzymes pyruvate
  dehydrogenase,
• a - ketoglutarate dehydrogenase ???
  transketolase
• ?????????????????? pentose phosphate
  pathway

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????? Lehninger et al, 1993
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VITAMIN B6
????? Murray et al, 1996
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Pyridoxal Pyridoxine Pyridoxamine
Pyridoxal phosphate (major form ??? vitamin
B6)
Enzyme Mg2, ATP requiring enzyme,
pyridoxal kinase
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Phosphorylation ??? Pyridoxal ??? Pyridoxal Kinase
????? Murray et al, 1996
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?????????? Pyridoxal Phosphate

• ???? coenzyme ??? enzymes ???????????????
• ????????? transamination ?? ???????
• synthesis ??? catabolism ??? amino acids
• ??? enzyme glycogen phosphorylase ??
• ??????? glycogenolysis

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Folic Acid (F)
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2
3
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10
4
glutamic acid
p-aminobenzoic acid
2-amino-4-oxo-6-methylpterin
Active form ???? coenzyme form ???
tetrahydrofolate(FH4 ???? H4)
????? http//www.indstate.edu/thcme/mwking/vitam
ins.html
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TETRAHYDROFOLATE
Function ??? tetrahydrofolate ???? carrier ???
one carbon
group
????? Nelson and Cox, 2000
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????? Murray et al, 1996
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Folate Derivative
????? http//www.indstate.edu/thcme/mwking/vitam
ins.html
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????? Murray et al, 1996
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One Carbon Transfer Reactions
????????????????? biosynthesis ??? serine ,
methionine, glycine,
choline, purine nucleotides ??? dTMP
dUMP
dTMP
N5,N10- Methylene FH4
FH2
FH4
reductase
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??????? methyl group ??? N5,N10-methylene FH4
????? dUMP ?????????????? dTMP ??? dihydrofolate
????? Murray et al, 1996