The position of mevalonic acid and isopentenyl pyrophosphate (3 methylbut 3 enyl pyrophosphate) as key intermediates in the biosynthesis of isoprenoid compounds is now firmly established, as also is the route by which mevalonic acid is converted into isopentenyl pyrophosphate. This transformation occurs through three ATP-dependent steps with the intermediate formation of mevalonate 5-phosphate ...

Vascular Calcification To the Editor: In their editorial on vascular calcification, Demer and Tintut1 incorrectly state that pyrophosphate reduces calcification by inhibiting alkaline phosphatase. Actually, the opposite is true. Alkaline phosphatase promotes calcification by reducing pyrophosphate levels. Pyrophosphate is a substrate for alkaline phosphatase,2 and this enzyme regulates pyrophos...

Purified bovine heart pyruvate dehydrogenase complex was used to investigate the effects of monovalent cations and cr-ketoisovalerate on pyruvate dehydrogenase (PDH) kinase inhibition by thiamin pyrophosphate. Initial velocity patterns for thiamin pyrophosphate inhibition were consistent with hyperbolic noncompetitive or hyperbolic uncompetitive inhibition at various K’ concentrations between 0...

A new terpene pyrophosphate synthetase (Enzyme II) distinct from the previously reported geranylgeranyl pyrophosphate synthetase (Enzyme I) has been isolated from extracts of Micrococcus lysodeikticus and partially purified. Enzyme II catalyzes the elongation of terpenoid ally1 pyrophosphates by isopentenyl pyrophosphate to long chain products. The order of effectiveness of various ally1 pyroph...

Numerous reports on the intermediate reactions in the biosynthesis of terpenoids were published after the characterization of mevalonic acid (1, 2) and the establishment of its conversion to squalene (3-8), cholesterol (9, lo), carotenes (ll-14), and rubber (15-17). These reports established the conversion of mevalonic acid to mevalonic 5-phosphate, mevalonic pyrophosphate, and A3-isopentenyl p...

The mean bone pyrophosphate was 0.360 +/- 0.15 mg/g in 8 controls and 1.22 +/- 1.39 mg/g bone in 27 uremic patients (P less than 0.0025). 13 of the 27 uremic patients had bone pyrophosphate levels greater than 2 SD above control values. The ash content of uremic bones with increased pyrophosphate levels (group II) was 56 +/- 9% as compared to 64 +/- 2% in control bones (P less than 0.01) and 60...

PC-1 is a nucleoside triphosphate pyrophosphohydrolase (NTPPPH) that generates pyrophosphate from the hydrolysis of ATP. PC-1 is the primary enzymatic generator of pyrophosphate in osteoblastic cells. The influence of PC-1 on tissue mineralization is complex (Figure 1). PC-1 activity increases extracellular levels of pyrophosphate. Pyrophosphate inhibits hydroxyapapatite crystal formation and p...

The prenyl transferase undecaprenyl p rophosphate synthetase was partially purified from the cytosolic fraction of Escherichia coli. Its enzymic products were characterized as a family of cis-polyprenyl phosphates, which ranged in carbon number from Cas to Czs. The enzyme is constituted of two subunits of approximately 30,000 molecular weight. A radiolabeled photolabile analogue of t,t-farnesyl...

Inorganic pyrophosphate can be accurately determined in 2 to 4 ml of serum or urine by an ion-exchange method. Pyrophosphate degradation by serum alkaline phosphatase and pyrophosphatase is stopped by adding to the serum 0.1 mmol of dithiothreitol (Cleland’s reagent) per liter. This method is suitable for screening large numbers of patients. All of the patients studied who had classical symptom...

The growth of a thiamine pyrophosphate auxotroph of Escherichi coli was inhibited by either thiamine or thiamine monophosphate, and the growth of a thiamine monophosphate auxotroph was inhibited by thiamine. The thiamine pyrophosphate-dependent oxidation of pyruvate was inhibited by thiamine with whole cells of the thiamine pyrophosphate auxotroph but not with cell extracts prepared from the sa...