Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Maximum inhibition of phenylalanine hydroxylase activity in the liver (85%) and in the kidney (50%) of suckling rats required the administration of over 9 mumol of p-chlorophenylalanine/10g body weight. Despite the decrease in the total activity from 184 to 34 units per 10g body weight, the injection of as much as 26 mumol of phenylalanine was required for its concentration in plasma to be still considerably elevated 12h later. In rats injected with p-chlorophenylalanine every 48h and with phenylalanine every 24h from 3 to 18 days of age, the hepatic and renal phenylalanine hydroxylase remained inhibited, whereas the activities of three other hepatic enzymes were unchanged. There was about 20% inhibition of brain and body growth, but no interference with the developmental formation of several cerebral enzymes (four dehydrogenases, hexokinase and glutaminase) was detected. In the course of this prolonged treatment, the phenylalanine concentrations in plasma increased gradually; on day 2 and day 8 (measured 12h after the last injection) they were 800 and 1395 nmol/ml respectively; on day 15, 12 and 18h after the usual injection, the values were 2030 and 1030 respectively as opposed to the 96 nmol in untreated rats. This degree of hyperphenylalaninaemia, persisting for 18h per day throughout a critical period of development, fulfils the primary criterion of a suitable animal model for phenylketonuria.
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PMID:The regulation of phenylalanine hydroxylase in rat tissues in vivo. The maintenance of high plasma phenylalanine concentrations in suckling rats: a model for phenylketonuria. 13 70

In phenylketonuria high levels of L-phenylalanine are present along with increased levels of phenylpyruvic acid. The present work shows that L-phenylalanine is a competitive inhibitor of human brain pyruvate kinase and phenylpyruvic acid is an inhibitor of human brain hexokinase. The enzymes have approximately the same K(i) for these inhibitors in adult and in fetal human brain. However, in the fetal human brain the absolute activities for both enzymes are less than 10 per cent of those found in the adult. Thus, the fetal brain enzymes may be more vulnerable to inhibition by these compounds in the phenylketonurics. The inhibition of human brain pyruvate kinase and hexokinase by L-phenylalanine and phenylpyruvic acid may have a role in the brain damage in phenylketonurics.
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PMID:Inhibition of human brain pyruvate kinase and hexokinase by phenylalanine and phenylpyruvate: possible relevance to phenylketonuric brain damage. 526 Sep 39