Biochemistry

сн-соон nh 2 Tyrosinase но сн-соон NH, Dofadecarboxylase Dioxiphenylalanine (DOPA) CH — CH — NH 2 Dofiminoxylase Norepinephrine Dopamine The concentration of noradrenaline in the nervous tissue depends on the intensity of its formation and the rate of destruction by the enzyme monoamine oxidase. Serotonin (5 -hydroxytryptamine). The activity of the neurotransmitter serotonin is associated with the function of higher nervous activity. The molecular mechanisms of serotonin function are still poorly understood. It was found that in small concentrations it increases the excitability of nerve nodes (ganglia), and in large concentrations it reduces the activity of brain acetylcholinesterase and inhibits the transmission of nerve excitation through central synapses. The inhibitory effect of serotonin on tissue respiration and ATP biosynthesis was also identified. It causes a spasm of arterioles, and also participates in the central regulation of blood pressure, body temperature, respiration, and renal filtration (it has an antidiuretic effect). Serotonin is referred to as radioprotectors due to its ability to react with free radicals formed in tissues upon irradiation. The source of serotonin is the amino acid tryptophan. Initially, it is oxidized to form oxytryptophan, which is then subjected to enzymatic decarboxylation with the participation of vitamin B 6 to form 5-hydroxytryptamine (serotonin). 279