They suggested combining the biomarker pattern of leukotriene E4, 3-hydroxypalmitoylcarnitine, aspartate, xanthosine
and methoxytryptophan for diagnosis of deficiencies caused infertility in normospermic/idiopathic infertile men (24).
Amination of xanthosine
5'-phosphate by purified enzyme from pigeon liver.
So, for their enzymatic studies, they chose to use xanthosine, a naturally occurring purine with a structure very similar to pi.
When they made short DNA template strands that included a kappa bead, the RNA and DNA polymerases assembled complementary strands with the xanthosine bases always opposite the kappa.
ITPA, a cytosolic enzyme present in many tissues (e.g., erythrocytes, leukocytes, heart, liver, endocrine glands), catalyzes the pyrophosphohydrolysis of ITP/dITP and xanthosine
triphosphate, thereby preventing accumulation of unusual nucleotides in cells and incorporation into RNA and DNA.
IMPDH (EC 188.8.131.52) (1) catalyzes the NAD-dependent oxidation of inosine 5'-monophosphate (IMP) to xanthosine
Xanthosine was not found in the urine samples of the two patients.
Xanthosine was detected in only one of these urine samples, in a low concentration (80 [micro]mol/mmol creatinine).
(3) Nonstandard abbreviations: MPA, mycophenolic acid; IMP-DH, inosine 5'-monophosphate dehydrogenase; XMP, xanthosine
5'-monophosphate; MMF, mycophenolate mofetil; MPAG, MPA glucuronide; HSA, human serum albumin; FBS, fetal bovine serum; DPBS, Dulbecco s PBS; and HBSS, Hanks' balanced salt solution.