PANERAI WATCHES. PANERAI. Founded in 1860, in the midst of the Renaissance in Florence, Italy, Panerai has mastered the arts of creativity, technical craftsmanship, and distinguished design. In the past two centuries, Panerai timepieces have served as crucial precision instruments for the Italian navy.
Regulation of Purine Biosynthesis. The PRPP amidotransferase enzyme exists as an active monomer and an inactive polymer (see Introduction to Metabolism Lecture). IMP, GMP and AMP all inactivate the enzyme causing a shift towards the polymerized inactive form. PRPP causes a shift towards the active monomeric form.
The dependence of purine biosynthesis on folic acid compounds at Steps 4 and 10 means that antagonists of folic acid metabolism (for example, methotrexate; see Figure 27.30) indirectly inhibit purine formation and, in turn, nucleic acid synthesis, cell growth, and cell division.