Neopterin

This interesting conversion of a five- into a six-membered heterocyclic ring was proven by the isolation of the enzyme GTP-cyclohydrolase from E. coli (71MI21600) and a similar one from Lactobacillus platarum (B-71MI21601) which catalyzes the reaction (300)(303). Dephosphorylation leads to 7,8-dihydro-D-neopterin (304), which is then cleaved in the side-chain to 6-hydroxymethyl-7,8-dihydropterin (305), the direct precursor of 7,8-dihy-dropteroic acid and 7,8-dihydrofolic acid (224). The alcohol (305) requires ATP and Mg " for the condensation with p-aminobenzoic and p-aminobenzoylglutamic acid, indicating pyrophosphate formation to (306) prior to the substitution step. 

Neopterin cyclophosphate Neopterin 2, 3 -cyclic phosphate Neopterin 3 -/3-D-glucuronide Neopterin 3 -triphosphate 6-(L-t/ reo-l, 2, 3 -Trihydroxypropyl)pterin ... 

J. R K. Huber and G. Lamprecht, Assay of neopterin in serum by means of two-dimensional high-performance liquid chromatography with automated column switching using tliree retention mechanism , 7. Chromatogr. B 666 223-232(1995). 

Neopterin cyclic phosphate (92) has been isolated as an intermediate in the biosynthesis of pteridines from GTP in Comamonas Tracer studies show that the phosphoryl group in (92) originates from the... 

Melmed, R. N., et al. (1989). Serum neopterin changes in HIV-infected subjects Indicator of significant pathology, CD4 T cell changes, and the development of AIDS. J. Acquir. Immune Defic. Syndr. 2,70-76. 

Murr C, Winklhofer-Roob BM, Schroecksnadel K, Maritschnegg M, Mangge H, Bohm BO, Winkelmann BR, Marz M and Fuchs D. 2009. Inverse association between serum concentrations of neopterin and antioxidants in patients with and without angiographic coronary artery disease. Atherosclerosis. In press. 

A strategy has been described for the synthesis of 2-ethyIthio-6-(3-hydroxy-1,2-0-isopropylidenepropyl)pteridin-4(3//)-one 90 which can be used as a useful intermediate for the conversion of neopterin to biopterin. Diaminopyrimidinone 86 reacts with D-arabinose phenylhydrazone 87, the obtained diastereomeric mixture 88 is converted into its isopropylidene derivative 89 which under oxidation conditions yields 90 <00H(53)1551>. 

Dihydroneopterin aldolase (Table 1, entry 8) Inhibitors (such as 33) of dihydro-neopterin aldolase were identified using high throughput X-ray-based fragment screening of a 10,000 member random library [43]. Structure-guided optimisation gave potent leads such as 35. 

During the course of chronic inflammatory processes of the central nervous system, the concentration of neopterin and /32-microglobulin probably reflects microglial activation and the extent of the intraparenchymal macrophage activation. Thus, as reported in one study (M4), patients with HIV infection without clinical neurological symptoms showed an inflammatory CSF reaction with an increase in /32-microglobulin and most notably in neopterin. Patients with HIV had higher values than did asymptomatic ones. 

In general, presuming no ongoing opportunistic CSN infection, /32-microglobulin and neopterin are good markers for central nervous system involvement in HIV infection. 

Altemus M, Cloitre M, Dhabhar FR (2003) Enhanced cellular immune responses in women with PTSD related to childhood abuse. Am J Psychiatry 160 1705-1707 Anisman H, Griffiths J, Matheson K, Ravindran AV, Merali Z (2001) Posttraumatic stress symptoms and salivary cortisol levels. Am J Psychiatry 158 1509-1511 Atmaca M, Kuloglu M, Tezcan E, Onal S, Ustundag B (2002) Neopterin levels and dexam-ethasone suppression test in posttraumatic stress disorder. Eur Arch Psychiatry Clin Neurosci 252 161-165... 

H. Wachter, D. Fuchs, A. Hausen, G. Reibnegger, G. Weiss, E. R. Werner, and G. Werner-Felmayer, Neopterin Biochemistry - Methods and Clinical Application , W. de Gruyter, Berlin, 1992. 

Native urine should be protected from light and stored at -20°C until processed. Oxidized urine sample can be stored at room temperature, but light protection is still recommended. Two procedures for the oxidation of urine (and other samples) are used (1) oxidation with manganese dioxide (Mn02) under acidic conditions, and (2) oxidation with iodine (iodine/potassium iodide, I2/KI) under acidic and basic conditions. The Mn02 oxidation method is a routine method used to quantify total pterins (fully oxidized neopterin, monapterin, biopterin, primapterin, isoxanthopterin, and pterin) the I2/KI method is used according to Fukushima and Nixon [11] for the differential oxidation of pterins and quantification of BH4. Total biopterin represents the sum of BH4, BH2, and fully oxidized biopterin. Under acidic conditions BH4 and BH2 are oxidized to biopterin, while under basic conditions only BH2 is oxidized to... 

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