Pea (Pisum sativum L.) seedling amine oxidase (EC 1.4.3.6) is the first amine oxidase to be crystallized that diffracts to atomic resolution (2.5 A). Extensive modifications of a published purification procedure were necessary to obtain protein that would give diffraction-quality crystals. Here we report the improved purification and also use this high-purity protein to reexamine some fundament...

The effects of asimilobine, an aporphine isoquinoline alkaloid, on dopamine biosynthesis and L-DOPA-induced cytotoxicity in PC12 cells were investigated. Asimilobine at concentration ranges of 0.05-0.2 microM showed a significant inhibition of intracellular dopamine levels for 24 h in a concentration-dependent manner with an IC50 value of 0.13 microM. Asimilobine at 0.15 microM inhibited tyrosi...

Despite being the most effective treatment for Parkinson's disease, L-DOPA causes a development of dyskinetic movements in the majority of treated patients. L-DOPA-induced dyskinesia is attributed to a dysregulated dopamine transmission within the basal ganglia, but serotonergic and noradrenergic systems are believed to play an important modulatory role. In this study, we have addressed the rol...

Esculetin has been described as an inhibitor of tyrosinase and polyphenol oxidase and, therefore, of melanogenesis. In this work, we demonstrate that esculetin is not an inhibitor but a substrate of mushroom polyphenol oxidase (PPO) and horseradish peroxidase (POD), enzymes which oxidize esculetin, generating its o-quinone. Since o-quinones are very unstable, the usual way of determining the en...

A simplified technique to detect polyphenol oxidase and melanin formation by Streptomyces culture filtrates was developed. The procedure involves the direct assay of pigment formation by the culture filtrate with 3-(3,4-dihydroxyphenyl)-L-alanine (L-dopa) as a substrate. Among cultures of the International Streptomyces Project, 34 failed to produce a diffusible dark brown pigment on peptone-yea...

Background: Aromatic L-amino acid decarboxylase (AADC) deficiency is caused by mutations in the dopa gene leading to reduced AADC enzyme activity; it characterized motor impairments and inability attain developmental milestones.

This paper describes the distribution of aromatic L-amino acid decarboxylase (AADC) activities in fourteen tissues (eight peripheral tissues and six brain regions) of semicarbazide (SC)-treated rats, using both L-DOPA and L-5-hydroxytryptophan (L-5-HTP) as substrates. The distribution of pyridoxal phosphate (PLP) was also measured in control and SC-treated rats. SC-treatment decreased the PLP c...

Few stably pigmented melanomas have been established as permanent lines in tissue culture, particularly from human sources. The availability of stably pigmented lines is a prerequisite for somatic cell hybridization studies to investigate the genetic control of pigment synthesis. Studies on the biochemistry of dopa oxidase would also be facilitated by the existence of additional permanent melan...