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Reaction specificity of native and nicked 3,4-dihydroxyphenylalanine decarboxylase.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 1999 Feb 26; Vol. 274 (9), pp. 5514-21. - Publication Year :
- 1999
-
Abstract
- 3,4-Dihydroxyphenylalanine (Dopa) decarboxylase is a stereospecific pyridoxal 5'-phosphate (PLP)-dependent alpha-decarboxylase that converts L-aromatic amino acids into their corresponding amines. We now report that reaction of the enzyme with D-5-hydroxytryptophan or D-Dopa results in a time-dependent inactivation and conversion of the PLP coenzyme to pyridoxamine 5'-phosphate and PLP-D-amino acid Pictet-Spengler adducts, which have been identified by high performance liquid chromatography. We also show that the reaction specificity of Dopa decarboxylase toward aromatic amines depends on the experimental conditions. Whereas oxidative deamination occurs under aerobic conditions (Bertoldi, M., Moore, P. S., Maras, B., Dominici, P., and Borri Voltattorni, C. (1996) J. Biol. Chem. 271, 23954-23959; Bertoldi, M., Dominici, P., Moore, P. S., Maras, B., and Borri Voltattorni, C. (1998) Biochemistry 37, 6552-6561), half-transamination and Pictet-Spengler reactions take place under anaerobic conditions. Moreover, we examined the reaction specificity of nicked Dopa decarboxylase, obtained by selective tryptic cleavage of the native enzyme between Lys334 and His335. Although this enzymatic species does not exhibit either decarboxylase or oxidative deamination activities, it retains a large percentage of the native transaminase activity toward D-aromatic amino acids and displays a slow transaminase activity toward aromatic amines. These transamination reactions occur concomitantly with the formation of cyclic coenzyme-substrate adducts. Together with additional data, we thus suggest that native Dopa decarboxylase can exist as an equilibrium among "open," "half-open," and "closed" forms.
- Subjects :
- 5-Hydroxytryptophan metabolism
Amination
Amino Acids chemistry
Circular Dichroism
Dopa Decarboxylase chemistry
Dopa Decarboxylase isolation & purification
Kinetics
Pyridoxal Phosphate metabolism
Recombinant Proteins chemistry
Recombinant Proteins isolation & purification
Recombinant Proteins metabolism
Substrate Specificity
Trypsin chemistry
Dopa Decarboxylase metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 274
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 10026165
- Full Text :
- https://doi.org/10.1074/jbc.274.9.5514