RESUMO
Phosphoribosyl pyrophosphate synthetase-1 (PRPS-1; EC 2.7.6.1.) catalyzes the binding of phosphate-group to ribose 5-phosphate, forming the 5-phosphoribosyl-1-pyrophosphate, which is necessary for the salvage pathways of purine and pyrimidine, pyridine nucleotide cofactors - NAD and NADP, the amino acids histidine and tryptophan biosynthesis. We aimed to investigate the impact of the different effectors on the activity of PRPS-1, to check the activity of the enzyme in vitro in a wide range of pHs and investigate some structural essentials of the enzyme, isolated from brain and liver. Molecular docking analyses were used to delineate the essentials of PRPS-1 structure, to find out the existence of enzyme effectors. Previously created by us kit was used for determination of the activity of PRPS-1 based on the formation of the inorganic phosphates (λ = 700 nm, Cary 60, Agilent, USA). Effectors impact on the activity of PRPS-1 was evaluated. In silico results of the effectors were later proven by in vitro experiments. For the first time biochemical essentials, including the existence of the multiple pockets, involvement of the amino acids into the processes of interactions with the effectors, evolutional of the sequence conservation, tissue depended Vmax differences were identified.
Assuntos
Fosforribosil Pirofosfato , Ribose-Fosfato Pirofosfoquinase , Difosfatos , Histidina , Simulação de Acoplamento Molecular , NAD , NADP , Nucleotídeos , Fosfatos , Fosforribosil Pirofosfato/química , Fosforribosil Pirofosfato/metabolismo , Purinas/metabolismo , Piridinas , Pirimidinas , Ribose-Fosfato Pirofosfoquinase/metabolismo , TriptofanoRESUMO
In the present paper the photodynamic effect of hypericin on superoxide dismutase activity and the possibility of reduction of hypericin phototoxicity by antioxidants were studied. It was shown an almost twice decrease in superoxide dismutase activity of red blood cells under the photosensitization by hypericin. The influence of antioxidants (ascorbic acid and quercetin) on hypericin photodynamic action has revealed that these antioxidants suppress or stimulate photohemolysis caused by hypericin. The photosensitization reaction realized by hypericin could be shifted from type II to type I or vice versa by manipulating the antioxidant concentration. Strengthening of photohemolysis by antioxidants in some concentrations indicates the switching of alternative mechanisms of hypericin photodynamic action and its complicated manner. Thus the selection of antioxidant concentrations is of extreme importance for changing the efficacy of photodynamic therapy with hypericin.
