Über die Spezifität der Aminosäure-decarboxylasen

Abstract

Die optisch natürlichen Formen der Aminosäuren Histidin, Tyrosin und Dioxy-phenylalanin (Dopa) können, wie wir in mehreren Arbeiten 1 ) gezeigt haben, durch tierisches Gewebe zu den entsprechenden Aminen decarboxyliert werden. Die decarboxylierenden Fermente finden sich in Niere und Leber fast aller untersuchten Tierarten, so z. B. bei Meerschweinchen, Kaninchen, Schwein, Hammel, Ziege und Huhn. Beim Meerschweinchen enthält auch der Dünndarm das auf Histidin bzw. Dioxy-pheiiylalanin eingestellte Ferment 2 ). Im Darm aller anderen Tierarten fehlt es.Die vorliegende Arbeit beschäftigt sich mit der Frage, ob es eine einheitliche Aminosäure-decarboxylase gibt, die 3 Aminosäuren also durch ein und dasselbe Ferment abgebaut werden, oder ob jede Aminosäure ihre eigene Decarboxylase besitzt. Um eine Entscheidung dieser Frage zu ermöglichen, haben wir Vergleichsversuche gemacht über das Verhältnis der Wirksamkeit, welche die Organe verschiedener Tierarten den 3 Aminosäuren gegenüber besitzen, ferner Versuche, durch selektive Adsorption das Vorliegen mehrerer Fermente nachzuweisen, und schließlich sogenannte Konkurrenzversuche (competition experiments).Schon aus der früher gemachten Beobachtung, daß die aus den Aminosäuren gebildeten Aminmengen größeuordnungsmäßig voneinander verschieden sind, geht eine gewisse Substratspezifität der Decarboxylasen hervor. Wurden z. B. von einem Organextrakt

Biosynthesis of Cerebral Phenolic Amines. I. In Vivo Formation of p-Tyramine, Octopamine, and Synephrine

“…The enzyme classically thought to be responsible for the formation of p-tyramine is L-aromatic amino acid decarboxylase, and although this enzyme has been shown to exist in tissues (see for instance Ref. 22) and be capable of decarboxylating certain of the amino acids (histidine, tryptophan, L-dopa, phenylalanine, and p-tyrosine), purified preparations (from various tissue sources) of the enzyme indicate that p-tyrosine decarboxylating activity is somewhat limited (23)(24)(25). That octopamine may be fomed by fl-hydroxylatisn of the alkyl side chain s f p-tyramine has been demonstrated both i~ tlivo (26)(27)(28)(29) and in uitro (30)(31)(32)(33), and the reaction seems to be analogous to the formation of noradrenaline from dopamine.…”

Kidney Enzymes and Essential Hypertension

“…The concentration of dihydroxyphenylalanine decarboxylase, for example, was found to be highest in guinea pig kidneys, while pig kidneys were about two-thirds as active and rabbit kidneys showed only one-fifth of the guinea pig kidney activity (92). As extracts from guinea pig and rabbit kidneys were, on the other hand, about equally active toward histidine, Holtz and co-workers (90) concluded that the decarboxylation of dihydroxyphenylalanine and of histidine was caused by two different enzymes. Tyrosine deearboxylase was recognized as a third independent enzyme, which could be adsorbed on kaolin leaving the previously mentioned two decarboxylases in solution (90).…”

“…As extracts from guinea pig and rabbit kidneys were, on the other hand, about equally active toward histidine, Holtz and co-workers (90) concluded that the decarboxylation of dihydroxyphenylalanine and of histidine was caused by two different enzymes. Tyrosine deearboxylase was recognized as a third independent enzyme, which could be adsorbed on kaolin leaving the previously mentioned two decarboxylases in solution (90). The kidneys of some species lack one or the other of the various decarboxylases.…”

The Essential Amino-acids

“…A second special function of histidine would seem to be in the formation of histamine which occurs in a variety of animal tissues and to which some physiological importance has been ascribed. The origin of histamine is not definitely known, but the experiments of Werle (1936Werle ( , 1940 suggest the de-amination of histidine in the kidney, and Holtz, Credner and Walter (1939) have observed that this reaction may be brought about by other organs.…”

“…The oxidation of phenylalanine to tyrosine has already been mentioned, and its further oxidation to 3 : 4-dihydro~yphenylalanine~ which is brought about in plants by tyrosinase, may also occur in animals (Bloch, 1927). The mode of formation of adrenaline from these substances has by no means been completely demonstrated, but it has been shown that various tissues, particularly liver and kidney, contain decarboxylases capable of converting tyrosine and dihydroxyphenylalanine to the corresponding amines (Holtz et al, 1939;Blaschko, 1942), and that tyramine is converted to adrenaline in the medulla of the adrenal glands (Schuler and Weidemann, 1935). Thyroxine, it was suggested by Harington and Barger (1927)) may be formed from two molecules of 3 : 5-di-iodotyrosine by the elimination (in effect) of a molecule of alanine, and di-iodotyrosine mayabe produced by the direct iodination of tyrosine.…”