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Spectral studies of the interaction of the substrate quinonoid 6 methyl di hydro pterine and the coenzyme nadh used as marker in the di hydro pteridine reductase ec 1.6.99.7 assay


, : Spectral studies of the interaction of the substrate quinonoid 6 methyl di hydro pterine and the coenzyme nadh used as marker in the di hydro pteridine reductase ec 1.6.99.7 assay. Journal of Inherited Metabolic Disease 5(3): 132-136

In dihydropteridine reductase assay the substrate quinonoid dihydropterine is reduced again to tetrahydropterine, concomitantly oxidizing NADH, the indicator of the enzyme assay. Because of the strong oxidizing capacity of quinonoid dihydropterine, the degree of spontaneous oxidation of NADH by the various substances used in the dihydropterine reductase assay was studied spectrally. A high degree of spontaneous oxidation of NADH by the substrate itself was found, which can be regulated by dithiotreitol, dependent on its concentration. The absorbance increase at 336 nm, due to the non-quinonoid dihydropterine formed spontaneously from its quinonoid form, strongly interferes with the absorbance decrease at 340 nm, due to the disappearance of NADH. The interference results in a shift of the absorbance maximum of NADH from 340 nm up to higher wavelengths. This phenomenon, expressing itself in various ways in blank and sample, is discussed with relevance to the validity of the current enzyme assays used in a further classification of hyperphenylalaninemic patients.

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van der Heiden, C.; Brink, W., 1982: Spectral studies of the interaction of the substrate 'quinonoid' 6-methyl dihydropterine and the coenzyme NADH used as marker in the dihydropteridine reductase assay. In dihydropteridine reductase assay the substrate quinonoid dihydropterine is reduced again to tetrahydropterine, concomitantly oxidizing NADH, the indicator of the enzyme assay. Because of the strong oxidizing capacity of quinonoid dihydropterine...

Bailey, S.W.; Ayling, J.E., 1983: 6 6 di methyl pterins stable quinoid di hydro pterin substrate for di hydro pteridine reductase ec 1.6.99.7 and tetra hydro pterin cofactor for phenyl alanine hydroxylase ec 1.14.16.1. The tautomeric structure of the cofactor product of aromatic amino acid hydroxlyases, quinoid dihydrobiopterin, is still unknown. Characterization of this molecule, which is also the substrate for [sheep liver] dihydropteridine reductase has been...

Armarego, W.L.F., 1979: Hydrogen transfer from tritium labeled 4 r and 4 s nadh in the reduction of racemic cis 6 7 di methyl 6 7 8h di hydro pterin with di hydro pteridine reductase ec 1.6.99.7 from human liver and sheep liver. Transfer of the 4-H atom, from NADH onto a N atom of dl-cis-6,7-dimethyl-6,7 (8H)-dihydropterin takes place stereospecifically from the B-face of NADH (transfer of the pro-S H atom) in the reduction of 4-R and 4-S (4-3H)NADH using dihydropteridine...

Abell, C.W.; Shen, R.S.; Gessner, W.; Brossi, A., 1984: Inhibition of di hydro pteridine reductase ec 1.6.99.10 by novel 1 methyl 4 phenyl 1 2 3 6 tetra hydro pyridine analogs. Dihydropteridine reductase converts dihydrobiopterin to tetrahydrobiopterin, the required cofactor for the hydroxylation of aromatic amino acids during the synthesis of dopamine and serotonin. Hydroxylated derivatives of 1-methyl-4-phenyl-1,2,3,6-...

Armarego W.L.F., 1979: The stereospecificity of 6 methyl 6 7 8h di hydro pterin and 6 7 di methyl 6 7 8h di hydro pterin cofactors towards di hydro pteridine reductase. Kisliuk, R: D G. M. Brown (ed.). Developments In Biochemistry, Vol. 4. Chemistry And Biology Of Pteridines; Proceedings Of The 6th International Symposium, La Jolla, Calif., Usa, Sept. 25-28, . Xxii 713p. Elsveier North-Holland; New York, N.y., Usa; Amsterdam, Netherlands. Illus. P1-6

Gal E.M.; Bybee J.A.; Sherman A.D., 1979: Biopterin part 5 de novo synthesis of di hydro biopterin evidence for its quinonoid structure and lack of dependence of its reduction to tetra hydro biopterin on di hydro folate reductase. Samples of quinonoid-L-erythrodihydrobiopterin (q-BH2) and quinonoid-6-methyl-dihydropterin (q-6-MPH2) were prepared by oxidation of L-erythro-5,6,7,8-tetrahydrobiopterin (BH4) and 5,6,7,8-tetrahydro-6-methylpterin (6-MPH4) and separated from D-er...

Lind K.E., 1969: Di hydro pteridine reductase a method for the measurement of activity and investigations of the specificity for nadh and nadph. European Journal Of Biochemistry: 497-502

Nakanisi, N.; Hirayama, K.; Yamada, S., 1982: A simple procedure for purification of nadh specific di hydro pteridine reductase ec 1.6.99.7 from mammalian liver. A simple and convenient purification method which can yield a homogeneous preparation from even a small amount of starting material was devised for NADH-specific dihydropteridine reductase from rat liver. The procedure is essentially composed of 2...

Reinhard, J.F.J. ; Chao, J.Y.; Smith, G.K.; Duch, D.S.; Nichol, C.A., 1984: A sensitive high performance liquid chromatographic fluorometric assay for di hydro folate reductase ec 1.5.1.3 in adult rat brain using 7 8 di hydro biopterin as substrate. A liquid chromatographic-fluorometric assay was developed to study the role of dihydrofolate reductase in adult rat brain since low levels of the enzyme preclude measurement by current spectrophotometric procedures. This method involves in vitro i...

Hasegawa, H., 1977: Di hydro pteridine reductase ec 1.6.99.7 from bovine liver purification crystallization and isolation of a binary complex with nadh. Dihydropteridine reductase [EC 1.6.99.7] was purified from bovine liver in 50% yield and crystallized. The physicochemical properties of the purified enzyme were quite similar to those of sheep liver dihydropteridine reductase. During the course o...