Sepiapterin reductase and ALR2 ("aldose reductase") from bovine brain.

摘要: Sepiapterin reductase (EC 1.1.1.153) catalyses the NADPH-dependent reduction of L-sepiapterin to 7,8-dihydrobiopterin as shown in Fig.1. It was first described silkworms where it be a separate enzyme from Dihydrofolate (Matsubara et al., 1963). has been purified livers various species & Akino, 1964; Matsubara 1966; Katoh, 1971) and homogeneous preparation obtained rat erythrocytes (Sueoka 1982; Smith, 1987). is dimeric protein with native relative molecular mass about 56,000 (rat erythrocytes; Sueoka 1982) potently inhibited by N-acetyl derivatives both serotonin dopamine such N-acetylserotonin, melatonin (Katoh 1982,1983), N-methoxyacetylserotonin N-chloroacetydopamine (Smith 1992) Ki values low micromolar range. Its probable function tetrahydrobiopterin (BH4) biosynthesis may participate diketo compound, 6-pyruvoyl-tetrahydropterin (6R-(1′, 2′-dioxopropyl)-tetrahydropterin), BH4 (see Nichol 1985). unclear whether alone keto groups or another also involved. (Milstien Kaufman, 1989a,b; Steinerstauch 1989). itself, however, no longer considered an intermediate de novo biosynthesis. Absence could give rise atypical form phenylketonuria Niederwieser, Although thought specific for 6-lactoyl side chain sepiapterin, recently found that broad substrate specificity towards carbonyl compounds can catalyse many “typical” aldoketo substrates p-nitrobenzaldehyde 9,10-phenanthrenequinone Sueoka, 1984,1989; 1985)