Xanthosine monophosphate is an intermediate in purine metabolism

Purine metabolism

-Biosynthesis:Purines are biologically synthesized as nucleotides and in particular as ribotides, i.e. bases attached to ribose 5-phosphate. A key regulatory step is the production of 5-phospho-α-D-ribosyl 1-pyrophosphate by PRPP synthetase, which is activated by inorganic phosphate and...

. It is a ribonucleoside monophosphate. It is formed from IMP via the action of IMP dehydrogenase

IMP dehydrogenase

IMP dehydrogenase is an enzyme that converts inosine monophosphate to xanthosine monophosphate:The structure of this enzyme is composed of a TIM barrel domain with two CBS domains inserted within a loop.It is inhibited by Mycophenolic acid.- Examples :...

, and it forms GMP

Guanosine monophosphate

Guanosine monophosphate, also known as 5'-guanidylic acid or guanylic acid and abbreviated GMP, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside guanosine. GMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase...

 via the action of GMP synthase

GMP synthase

-Enzymology:In enzymology, a GMP synthase is an enzyme that catalyzes the chemical reactionThe 4 substrates of this enzyme are ATP, xanthosine 5'-phosphate, L-glutamine, and H2O, whereas its 4 products are AMP, diphosphate, GMP, and L-glutamate.This enzyme belongs to the family of ligases,...

.

Clinical significance

Xanthylic acid can be used in quantitative measurements of the inosine monophosphate dehydrogenase enzyme activities in purine metabolism, as recommended to ensure optimal thiopurine

Thiopurine

The thiopurine drugs are purine antimetabolites widely used in the treatment of acute lymphoblastic leukemia, autoimmune disorders , and organ transplant recipients.Metabolism is catalyzed by S-methyltransferase....

 therapy for children with acute lymphoblastic leukaemia (ALL).