title: The effect of cations on the amidase activity of human tissue kallikrein: 1-linear competitive inhibition by sodium, potassium, calcium and magnesium. 2-linear mixed inhibition by aluminium.
abstract: Hydrolysis of D-valyl-L-leucyl-L-arginine p-nitroanilide by human tissue kallikrein (hK1) was studied in the absence and in the presence of increasing concentrations of the following chloride salts: sodium, potassium, calcium, magnesium and aluminium. The data indicate that the inhibition of hK1 by sodium, potassium, calcium and magnesium is linear competitive and that divalent cations are more potent inhibitors of hK1 than univalent cations. However the inhibition of hK1 by aluminium cation is linear mixed, with the cation being able to bind to both the free enzyme and the ES complex. This cation was the best hK1 inhibitor. Aluminium is not a physiological cation, but is a known neurotoxicant for animals and humans. The neurotoxic actions of aluminium may relate to neuro-degenerative diseases.
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, C. P. 689, 30123-970 Belo Horizonte, MG, Brazil.
authors.forename: Marinez Oliveira
authors.initials: MO
authors.lastname: De Sousa
authors.forename: Marcelo Matos
authors.initials: MM
authors.lastname: Santoro
authors.forename: Amintas Fabiano
authors.initials: AF
authors.lastname: De Souza Figueiredo
mesh_terms: D000535:Aluminum / Q000494:pharmacology; D000581:Amidohydrolases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D001667:Binding, Competitive; D002118:Calcium / Q000494:pharmacology; D002412:Cations / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D006868:Hydrolysis; D016014:Linear Models; D008274:Magnesium / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D020840:Tissue Kallikreins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism
chemical_list: D002412:Cations; D004791:Enzyme Inhibitors; D012964:Sodium; D000535:Aluminum; D020840:Tissue Kallikreins; D000581:Amidohydrolases; C019665:amidase; D008274:Magnesium; D011188:Potassium; D002118:Calcium