{'fraction_non_alphanumeric': 0.040354330708661415, 'fraction_numerical': 0.013779527559055118, 'mean_word_length': 5.436708860759493, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Inhibition of Monoamine Oxidase by 3,4‐Dihydroxyphenylserine

Abstract: The effects of diastereomers of 3,4‐dihydroxyphenylserine (DOPS) on the enzyme activity of monoamine oxidase (MAO) in human placenta and liver mitochondria were examined. Both l‐ and d‐threo‐DOPS were found to inhibit MAO‐A in human placental mitochondria in competition with the substrate, and the Ki values for l‐ and d‐threo‐DOPS obtained were 68.3 and 125 μM, respectively. The inhibitory effect of l‐threo‐DOPS on both MAO‐A and ‐B activity was confirmed in human liver mitochondria, and MAO‐A was found to be more sensitive to the inhibitor. Other isomers of DOPS, l‐ and d‐erythro‐DOPS, were found to inhibit MAO activity, but the inhibition was noncompetitive with the substrate. The inhibitory effects of DOPS isomers were not affected by the presence of NSD‐1055, an inhibitor of aromatic l‐Amino acid decarboxylase, suggesting that the inhibition is the direct effect of DOPS, and not of norepinephrine produced by the decarboxylase.