Interaction
of Aromatic L-Amino-Acid Decarboxylases with Pyridoxal Phosphate
NGO TRAN, Department of
Nuclear Medicine and Radiobiology, Centre Hospitalier Universitaire, Sherbrooke,
Quebec, Canada
International Journal of Biochemistry,
2: 700-704, 1971
The decarboxylation of 3,4-dihydroxyphenylalanine (dopa)
to dopamine by aromatic L-amino-acid decarboxylases (pyridoxal-phosphate
(PLP)-dependent enzymes) has been demonstrated in animal (Sandler and
Ruthven, 1969) and human (Vogel, MacFarland, and Prince, 1970) tissues.
To appreciate the role of pyridoxal phosphate in both its binding process
to the protein and its enzymatic reaction, the interactions of PLP with
aromatic L-amino-acid decarboxylases, i.e., L-tyrosine decarboxylase and
L-phenylalanine decarboxylase, and furthermore the activities of such
enzyme-PLP complexes involved in the decarboxylation of dopa have been
studied.
ABSTRACT:
1) The rates of binding of pyridoxal phosphate to L-phenylalanine
decarboxylase and L-tyrosine decarboxylase of Streptococcus Faecalis have
been studied by measuring the changes in spectral absorbance at 420-nm.,
200-nm., and 380-nm. peaks.
2) These spectral changes are considered to be the first direct evidence
for the binding process of pyridoxal phosphate and aromatic L-amino-acid
decarboxylases.
3) The activities of such enzyme-pyridoxal phosphate complexes involved
in the decarboxy --lation of 3,4-dihydroxyphenylalanine have been measured
continuously using a combined vibrating-reed electrometer/ionization chamber
method.
Int J. Biochemistry, 2: 700-704, 1971
Ngo Manh Tran, M.D., Ph.D.
