- * Purine Ring
- N9 (from glutamine hydrolysis) (with the ribose-5-phosphate attached).
- C4, C5, N7 (from Glycine)
- C8 (from THF)
- N3 (from glutamine hydrolysis)
- C6 (from CO2)
- N1 (from Aspartate)
- C2 (from THF)
- Double bonds between C8 and N7, C4 and C5, and C2 and N3.
- C6 carbon is double-bonded to oxygen.
- The bases are: adenine and guanine
- The ribonucleosides (meaning the sugars + bases) are: adenosine and guanosine
- The ribonucleotides (meaning the sugars + bases + 5'-monophosphates) are: adenylate (AMP) and guanylate (GMP)
- The diphosphates are: adenosine diphosphate ADP and guanosine diphosphate GDP
- The triphosphates are: adenosine triphosphate ATP and guanosine triphosphate GTP
Purine Ring
Overview
Purine biosynthesis occurs via two key pathways:
De Novo synthesis
- The base, itself, is synthesized from scratch
- from such components as: ATP, key amino acids, N10-formyltetrahydrofolate, CO2).
- Then attached to the activated (phosphorylated) ribose (sugar) to form the desired nucleotide.
Salvage pathway
- The base is reattached to the phosphorylated ribose (ribose phosphate) to form the nucleotide.
Nucleoside vs. Nucleotide
- A nucleoside is a BASE + SUGAR
- A nucleotide is a BASE + SUGAR + PHOSPHATE