Uridylic acid biosynthetic pathway

Carboxylation followed by a later decarboxylation is an important pattern in other biosynthetic pathways, too. Sometimes the decarboxylation follows the carboxylation by many steps. For example, pyruvate (or PEP) is converted to uridylic acid (Eq. 17-41 details are shown in Fig. 25-14) ... 

The biosynthetic pathway which leads to the pyrimidine nucleotides is described in the section on pyrimidinecarboxylic acids, where orotic acid is shown to be an intermediate on the route to uridylic acid (UMP). This is then converted to the di- and triphosphates in the presence of ATP and... 

Relatively little is known about the metabolism and biological action of PF, mainly because of the lack of adequate analytical methodology. In reversal studies of the PF-induced inhibition of vaccinia virus vitro (2), it was revealed that the activity of PF is reversed by uridine and uridylic acid, but not by cytidine or orotidine. This led to the suggestion (5) that the mode of action of PF might be the inhibition of the dje novo biosynthetic pathway of pyrimidine nucleotides. The most likely mode of action of PF is shown in Fig. 1. 

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