Kawakishi, "Formation of protein-bound 3,4-dihydroxyphenylalanine
and 5-S-cysteinyl-3,4-dihydroxyphenylalanine as new cross-linkers in gluten," Journal of Agricultural and Food Chemistry, vol.
Simultaneous liquid-chromatographic determination of 3,4-dihydroxyphenylglycol, catecholamines, and 3,4-dihydroxyphenylalanine
in plasma, and their responses to inhibition of monoamine oxidase.
The biochemistry of catecholamines--epinephrine, norepinephrine, 6-hydroxydopamine, 6-aminodopamine, 3,4-dihydroxyphenylalanine
(dopa), and dialuric acid--is well established.
These proteins contain the unusual amino acid 3,4-dihydroxyphenylalanine
(DOPA) which is believed to be the site of cross-linking.
Polyphenol oxidase activity was determined for each sample by a modification of the L-DOPA (3,4-dihydroxyphenylalanine
) assay described by Anderson and Morris (2001).
Here, for example, insult A targets the vesicular monoamine transporter in which DA is stored; insult B attacks the enzyme converting tyrosine to DOPA (3,4-dihydroxyphenylalanine
) and thus the DA metabolic pathway; insult C strikes the metabolism of DOPAC (3,4-dihydroxyphenylacetic acid) to HVA (bomovanillic acid); and insult D hits the DA transporter that takes DA back up from the synaptic cleft postrelease.
The dopamine precursor 3,4-dihydroxyphenylalanine
(levodopa or L-dopa) is the most efficient treatment to control motor deficits of PD patients [28,29].
This enzyme catalyzes the oxidation of L-tyrosine to 3,4-dihydroxyphenylalanine
(DOPA) and of DOPA to dopaquinone, which is then processed to dopachrome and eumelanin in the absence of cysteine (Cys) .
Pye et al., "Quantitation of protein-bound 3-nitrotyrosine and 3,4-dihydroxyphenylalanine
by high-performance liquid chromatography with electrochemical array detection," Analytical Biochemistry, vol.
Notewor-thily, tyrosine residues of both Pc-1 and Pc-2 are post-translationally modified into 3,4-dihydroxyphenylalanine
(DOPA) by the addition of a hydroxyl group (Waite et al., 1992).