The pyrophosphorylysis of adenosine diphosphate glucose and adenosine diphosphate mannose

• 1.

  1. The biosynthesis of adenosine diphosphate glucose and adenosine diphosphate mannose from adenosine triphosphate and respectively glucose 1-phosphate and mannose 1-phosphate has been observed in extracts from mammalian tissues. The reaction is reversible in the presence of the nucleoside diphosphate sugar and pyrophosphate.

• 2.

  2. Two different enzymes are probably responsible for the reactions with either adenosine diphosphate glucose or adenosine diphosphate mannose.

• 3.

  3. Adenosine diphosphate mannose may be synthesized by the same enzyme which catalyzes the biosynthesis of guanosine diphosphate mannose and inosine diphosphate mannose.

• 4.

  4. Evidence is presented that adenosine diphosphate glucose pyrophosphorylase (ATP: α-d-glucose-1-phosphate adenylyltransferase) may be a specific enzyme.

• 5.

  5. The relative levels of nucleoside diphosphate hexose pyrophosphorylases have been measured in different extracts from mammals, plants or yeast. From these data the possible significance of adenosine diphosphate glucose pyrophosphorylase in mammals is discussed.