L-Dopa and the treatment of extrapyramidal disease.

摘要: Publisher Summary This chapter discusses the L-dopa and treatment of extrapyramidal disease. Although systemic administration elevates intraneuronal concentrations both dopa DA, dietary tyrosine serves as natural precursor these catechols in central nervous system. L-Tyrosine is hydroxylated meta-position to by hydroxylase. The enzyme requires molecular oxygen, ferrous iron, a reduced pteridine. It specific for hydroxylation L-tyrosine or L-phenylalanine, but ineffective D isomers m-tyzosine thus, differs from rather nonspecific phenol-oxidizing enzyme, tyrosinase. Tyrosine phenylalanine each inhibits hydroxylase other amino acid. Dopa decarboxylase that found soluble portion cell homogenates catalyzes conversion DA. pyridoxal phosphate-requiring has been thought act on all aromatic 1-amino acids including phenylalanine, tryptophan, 5-hydroxytryptophan, histidine. distribution ubiquitous outside within system, high gut mucosa walls brain capillaries.