Pyridoxal-5-phosphate-ethylenediamine

N,N -Bis-(pyridoxal-5-phosphate)ethylenediamine-N,N -diacetic acid synthesis... 

In addition to pyridoxal phosphate it has been reported that 5HTP decarboxylase also seems to require a metal. This metal requirement stems from the finding that chelating agents such as ethylenediamine tetraacetate inhibit activity (Beiler and Martin, 1954). Inhibition by chelating agents has been confirmed in the reviewer s laboratory. 

Interesting experiments with chemical models that outline the functions of both pyridoxal phosphate and have been carried out by Erode and Jaenicke (4S)- These workers observed that serine was stable at pH 5 in the presence of either pyridoxal or of an JNT. AT -diarylethylenediamine alone. However, the simultaneous addition of both compounds and A1+++ rendered the serine unstable and resulted in the nonenzjonic splitting of serine to glycine and formaldehyde. The authors conclude that the 3-carbon of serine reacts similarly with the ethylenediamine structure of FH4 in the enzymic reaction. 

The thermodynamic and kinetic characteristics of an intramolecular transimination reaction observed in solutions containing pyridoxal-5-phosphate and ethylenediamine have been investigated (75JA6530). The open-chain structure Schiff bases and the cyclic tautomers such as 54 are in equilibrium in aqueous solution over the pH range 7.5-14, but these equilibria are rather complex owing to the different states of the ionization (protonation) in both tautomers. The ring-chain equilibrium constant (the sum of all cyclic tautomers versus all open-chain tautomers) varies by less than a factor of 4 over the pH range 7-14. At pH 14, KT = 1.2 at pH 10,... 

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