Decarboxylation of 3,4-dihydroxyphenylalanine (DOPA) by erythrocytes: a reaction promoted by methemoglobin and other ferriheme proteins.
نویسندگان
چکیده
The decarboxylation of DOPA by erythrocyte hemolysates differs from DOPA decarboxylation catalyzed by aromatic aminoacid decarboxylases that contain vitamin B(6) in several significant respects. The ability of erythrocyte hemolysates to decarboxylate DOPA is associated with interaction between DOPA and methemoglobin; the ferriheme protein is reduced and DOPA is decarboxylated, probably after oxidation to a quinone intermediate. An analogous reaction takes place between DOPA and other ferriheme proteins, such as metmyoglobin and cytochrome c. This phenomenon may be of significance in relation to the side effects observed in patients with Parkinson's disease who are treated with very large doses of DOPA.
منابع مشابه
Reactions of DOPA (3,4-dihydroxyphenylalanine) decarboxylase with DOPA.
The study of DOPA (3,4-dihydroxyphenylalanine) decarboxylase by steady-state methods is difficult because multiple reactions occur. The reaction with DOPA was studied at enzyme concentrations between 20 and 50 micrometer by direct observation of the bound coenzyme by using stopped-flow and conventional spectrophotometry. Four processes were observed on different time scales and three of these w...
متن کامل3,4-Dihydroxyphenylalanine (dopa) decarboxylase activity in the arthropod nervous system.
1. When homogenates of brains from mature adult locusts (Locusta migratoria) were incubated with l-3-(3,4-dihydroxyphenyl)[3-(14)C]alanine the major radioactive metabolite was dopamine, suggesting the presence of a dopa (3,4-dihydroxyphenylalanine) decarboxylase. 2. Decarboxylation of l-dopa by this tissue, measured under optimum conditions by a radiochemical method, was 21mumol of CO(2)/h per ...
متن کاملEffect of protein ingestion on urinary dopamine excretion. Evidence for the functional importance of renal decarboxylation of circulating 3,4-dihydroxyphenylalanine in man.
Since dietary protein increases urinary dopamine (DA) excretion in animals, this study was undertaken to assess the role of DA production in the acute changes in renal function following protein ingestion in man. Excretion of DA, sodium, potassium, water, solute, and creatinine were measured in six normal men in 30-min intervals over 5 h after oral ingestion of protein and/or carbidopa, an inhi...
متن کاملA Crystallization-Induced Asymmetric Transformation using Racemic Phenyl Alanine Methyl Ester Derivatives as Versatile Precursors to Prepare Amino Acids
L-Tyrosine and L-Dopa are the precursors in the biological synthesis of amine neurotransmitters. On the other hand, phenylalanine as an aromatic amino acid (AAA) is a precursor in the synthesis of L-Tyrosine and L-Dopa. For some substrates such as amino acids, resolution by the formation of diastereomers offers an attractive alternative. Among different methods in this case, crystallization-ind...
متن کاملOxidation of tyrosine residues in proteins by tyrosinase. Formation of protein-bonded 3,4-dihydroxyphenylalanine and 5-S-cysteinyl-3,4-dihydroxyphenylalanine.
A simple and rapid method was developed for the determination of 3,4-dihydroxyphenylalanine (dopa) and 5-S-cysteinyl-3,4-dihydroxyphenylalanine (5-S-cysteinyldopa) in proteins with the use of high-pressure liquid chromatography. With this method, it is demonstrated that mushroom tyrosinase can catalyse hydroxylation of tyrosine residues in proteins to dopa and subsequent oxidation to dopaquinon...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Proceedings of the National Academy of Sciences of the United States of America
دوره 69 9 شماره
صفحات -
تاریخ انتشار 1972