Calcium pyrophosphate | Farnesyl pyrophosphate | 5'-Phosphoribosyl-4-carboxy-5-aminoimidazole |
This bifunctional enzyme is named UMP synthase and it also catalyzes the preceding reaction in pyrimidine nucleotide biosynthesis, the transfer of ribose 5-phosphate from 5-phosphoribosyl-1-pyrophosphate to orotate to form OMP.
The conversion of ATP, L-aspartate, and 5-aminoimidazole-4-carboxyribonucleotide (CAIR) to 5-aminoimidazole-4-(N-succinylcarboxamide) ribonucleotide, ADP, and phosphate by phosphoribosylaminoimidazolesuccinocarboxamide synthetase (SAICAR synthetase) represents the eighth step of de novo purine nucleotide biosynthesis.
Calcium pyrophosphate crystals are seen in pseudogout (also known as calcium pyrophosphate deposition disease or, CPPD).