Quinonoid dihydropterin reductase—II: Regional and subcellular distribution of rat brain enzyme
The regional and subcellular distribution of quinonoid dihydropterin reductase (DHPR, EC 1.6.99.7) was studied in the rat brain. In addition, the subcellular distribution of the enzyme was studied in the rat liver. The activity of rat brain DHPR was found to be lowest in the cerebral cortex (0.14 un...
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Veröffentlicht in: | Biochemical pharmacology 1978, Vol.27 (15), p.1947-1953 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The regional and subcellular distribution of quinonoid dihydropterin reductase (DHPR, EC 1.6.99.7) was studied in the rat brain. In addition, the subcellular distribution of the enzyme was studied in the rat liver. The activity of rat brain DHPR was found to be lowest in the cerebral cortex (0.14 unit mg
−1) and highest in the posterior colliculus (2.35 units mg
−1). The distribution of brain DHPR correlated positively with the distribution of aromatic-
l-amino acid decarboxylase but not with the distribution of tyrosine hydroxylase or tryptophan deearboxylase. However, this correlation was not observed in the caudate nucleus which contains low DHPR activity and high aromatic-
l-amino acid decarboxylase and tyrosine hydroxylase activities. This finding is an indication that the amount of DHPR in the caudate nucleus may be rate limiting. The distribution profiles of brain and liver DHPR were found to be similar to that of lactate dehydrogenase; for both enzymes the greatest specific activity was found in the soluble fraction, indicating that DHPR is a cytoplasmic enzyme. |
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ISSN: | 0006-2952 1873-2968 |
DOI: | 10.1016/0006-2952(78)90010-2 |