Chap_22_2010_v2

If deficiency in arg then gsa can be converted to orn

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Unformatted text preview: rted to Orn (See Chap 18) Eight steps are necessary to form Arg in bacteria (de novo synthesis of ornithine ) 1 The α-amino group of Glu is acetylated to avoid cyclization 2 The acetyl group is removed after transamination Urea cycle 5 H2O 3 4 Ornithine CH3COON- acetylornithinase 11 Urea cycle and related reactions aa oxaloacetate Aminotransferase α -keto acid keto acid Aspartate aa Ornithine transcarbamoylase α-ketoglutarate Aminotransferase α -keto acid keto acid glutamate Argininosuccinate Argininosuccinate synthase synthase Malate Arginase Arginine fumarase One of the amino group of urea comes from Carbamoyl phosphate, the other comes from Aspartate Malate dehydrogenase B.3-Phosphoglycerate amino acids family 4 steps 1 step 2 steps Non-essential aas 12 This pathway is universal among organisms Formation of Gly from Ser 13 Reminder from last lecture! Transfer of one-carbon groups using tetrahydrofolate Biosynthesis of Cys from Ser in bacteria and plants 14 Bacteria and plants produce the reduced sulfur from environmental sulfates Biosynthesis of Cys from serine and homocystein in mammals Reminder from last lecture! Transfer of one-carbon groups using S-Adenosyl -methionine 15 Biosynthesis of Cys from serine and homocystein in mammals 16...
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