Nucleotide Metabolism (Purine Biosynthesis)

Flashcards of key vocabulary terms related to Purine Biosynthesis

Purine

A nitrogenous base with a two-ring structure; includes adenine and guanine.

Pyrimidine

A nitrogenous base with a one-ring structure; includes cytosine, thymine, and uracil.

Ribonucleotide

A nucleotide containing ribose as its pentose sugar.

Deoxyribonucleotide

A nucleotide containing deoxyribose as its pentose sugar.

De novo pathway

A pathway for nucleotide synthesis that begins with metabolic precursors like amino acids, ribose 5-phosphate, CO2, and NH3.

Salvage pathway

A pathway that recycles free bases and nucleosides released from nucleic acid breakdown.

Phosphoribosyl pyrophosphate (PRPP)

An important precursor in both de novo and salvage pathways for nucleotide synthesis; retains the ribose structure in the product nucleotide.

Adenosine 5-monophosphate (AMP)

A purine nucleotide containing the adenine base; also known as adenylate.

Guanosine 5-monophosphate (GMP)

A purine nucleotide containing the guanine base; also known as guanylate.

Inosine Monophosphate (IMP)

Basic pathway for biosynthesis of purine ribonucleotides

Ribose phosphate pyrophosphokinase

Enzyme responsible for activation of ribose-5-phosphate

5-phosphoribosyl-a-pyrophosphate (PRPP)

Product of the activation of ribose-5-phosphate, precursor in pyrimidine nucleotide and amino acid biosynthesis

Amidophosphoribosyl transferase

Enzyme responsible for acquisition of purine atom 9

Glycinamide ribonucleotide (GAR)

Product of reaction of b-phosphoribosylamine with ATP and glycine via glycinamide synthetase

Formylglycenamide ribonucleotide (FGAR)

Product of formylation of free a-amino group of GAR via GAR transformylase

Formylglycinamidine ribonucleotide (FGAM)

Product of amide amino group transfer from glutamine to form formylglycinamidine ribonucleotide (FGAM)

5-aminoimidazole ribonucleotide (AIR)

Product of the closing of the imidazole ring or formation of 5-aminoimidazole ribonucleotide

Carboxyaminoimidazole ribonucleotide (CAIR)

Product of acquisition of C6 with the introduction of HCO3

5-aminoimidazole-4-(N-succinylocarboxamide) ribotide (SAICAR)

Product of the acqusition of N1 from aspartate in an amide condensation reaction

5-aminoimidazole-4-carboxamide ribotide (AICAR)

Product of elimination of fumarate

5-formaminoimidazole-4-carboxamide ribotide (FAICAR)

Product of the acquisition of C2 from another formylation reaction

Inosinate (IMP)

Product of cyclization or ring closure

Glutamine-PRPP amidotransferase

Allosteric enzyme inhibited by IMP, AMP, and GMP

IMP dehydrogenase

Enzyme inhibited by GMP excess

Adenylosuccinate synthetase

Enzyme inhibited by adenylate accumulation

APRT (adenine phosphoribosyl transferase)

Enzyme for adenine in the purine salvage pathway.

HGPRT (hypoxanthine guanine phosphoribosyl transferase)

Enzyme for guanine or hypoxanthine in the purine salvage pathway.

Lesch-Nyhan syndrome

A genetic disorder caused by a deficiency of HGPRT, leading to hyperuricemia, gout, and neurological problems including self-mutilation.

Allopurinol

A treatment for Lesch-Nyhan syndrome that decreases the formation of uric acid.