Nitrogen Metabolism

Entry point reaction for N2 to join bioprocesses

glutamate and glutamine

Glutamate to glutamine enzyme

glutamine synthetase

E.coli glutamine synthetase structure

has 12 identical subunits

Allosteric regulation of GS

byproducts of glutamine can inhibit reaction of glutamate to glutamine

Products that inhibit GS

AMP, CTP, tryptophan, histidine, carbamoyl phosphate, glucosamine 6-P

Covalent modification of GS

modification of each subunit reduces activity incrementally

Transamination enzyme

transaminases

Transamination coenzyme

pyridoxal phosphate (PTP)

1-C transfer part 1

carboxylases

1-C transfer coenzyme (carboxylase)

biotin

1-C transfer part 2

methyltransferase

1-C transfer coenzyme (methyltransferase)

tetrahydrofolate, SAM

Amide group transfer

glutamine amidotransferse

Amide group transfer coenzyme

ATP

a-ketoglutarate forms

glutamate

a-ketoglutarate to glutamate enzyme

glutamate dehydrogenase

Glutamate can form

glutamine, proline, arginine, or go into urea cycle (in mammals)

3-phosphoglycerate forms

serine

Serine can form

glycine and cysteine

Oxaloacetate transamination

aspartate

Aspartate amidation

asparagine

Acute lymphoblastic leukemia (ALL) cells

require asparagine for growth (chemotherapy uses asparaginase)

Pyruvate transamination

alanine

Phenylalanine to tyrosine

phenylalanine hydroxylase

Bile pigment step 1

heme to biliverdin

Bile pigment step 1 enzyme

heme oxygenase

Bile pigment step 2

biliverdin to bilirubin

Bile pigment step 2 enzyme

biliverdin reductase

Bile pigment step 3

bilirubin goes to bile or bilirubin forms bilirubin diglucuronoid

Bile pigment step 3 enzyme

glucuronosyl transferase

Bile pigment step 4

bilirubin to urobilinogen

Bile pigment step 5

urobilinogen forms urobilin and stercobilin

Creatine is produced from

glycine, arginine, methionine

Phosphocreatine

energy buffer of the muscle cells

Spermine and spermidine precursors

SAM, methionine, ornithine

Glutamate to Y-aminobutyrate (GABA) enzyme

glutamate decarboxylase (PLP) (CO2 exits reaction)

Histidine to histamine enzyme

histidine decarboxylase (PLP) (CO2 exits reaction)