Calf intestine alkaline phosphatase, NADH, NADPH, DHPR, peroxidase, leupeptin, and pepstatin were from Roche.
2] plates were harvested, washed with phosphate-buffered saline, and kept at -80[degrees]C until analyzed for PTPS, DHPR and SR.
DHPR activity is necessary to stabilize the formation of B[H.
2], 1 mmol/L NADPH, 1 mmol/L NADH, 3 mU of SR, 220 mU of DHPR, and 60 [micro]mol/L dihydroneopterin triphosphate in a final volume of 110 [micro]L.
The pterin derivative 6,7-dimethyltetrahydropterin was oxidized in situ by peroxidase in the presence of H202 to q-6,7-dimethyldihydropterin and thus was recycled for the DHPR reaction.
REFERENCE VALUES FOR PTPS, SR, AND DHPR ACTIVITIES IN UNSTIMULATED CELLS
DHPR activity was also similar in amniocytes and fibroblasts, as well as in males and females (males, 5-7.
Furthermore, both neopterin and biopterin are very low in GTPCH deficiency, neopterin is high and biopterin low in PTPS deficiency, and biopterin concentrations are very high in DHPR deficiency (8, 41).
PTPS and DHPR activities are measurable in many different tissues and cells such as erythrocytes (21, 22), fibroblasts (23, 24), and liver (19, 20).
On the other hand, prenatal diagnosis of PTPS and DHPR deficiency should be possible because the activities of these two enzymes are well detectable in amniocytes (Table 1).
We observed that cells collected in the first year of life showed higher PTPS and DHPR activities than cells collected at a later age.