SPECIFIC INCREASE OF L-DOPA LEVELS IN PLASMA UPON INFUSION OF TRYOSINASE CONTAINING LIPOSOMES

1. The present paper reports the effects of liposome-entrapped tyrosin ase (EC 1.14.18.1. L-Tyrosine, L-3,4-dihydroxyphenylalanine: oxygen ox idoreductase) infusion on the catecholamine contents of rat plasma. Th e actions of liposomes and free tyrosinase have also been investigated . 2. From the experiments, evidence has been obtained that liposome-en trapped tyrosinase is able to affect specifically L-3,4-dihydroxypheny lalanine (L-DOPA) levels which increase dramatically. 3. The possible use of liposome-entrapped tyrosinase to raise L-DOPA levels in catecho lamine related disorders is discussed. 4. Liposomes without tyrosinase provoke no significant changes of catecholamine or L-DOPA levels whil e free tyrosinase does induce a change but in a less constant fashion than the liposome-entrapped enzyme.