title: [Direct measurement of the antivitamin action of parenterally injected thiaminase].
abstract: Thiaminase (EC 2.5.1.2) from freshwater bivalve molluscs is a polycosubstrate enzyme, which is resistant to temperatures below 55 degrees. The activation energy of the enzyme with cystein is 15077 cal/mole, with aniline--15948 cal/mole. Thiaminase when injected parenterally to albino mice 2 hrs after injection of [2-14C]thiamine causes an extensive destruction of labelled vitamin b1, which is evidenced from the [14C]thiazole content in urine, liver and kidneys. The total radioactivity and the content of [14C]thiazole in the urine samples collected within 6 hrs after thiamine injection are increased. Cysteine and histidine in combination with thiaminase have no activating effect similar to that observed "in vitro". In the experimental series when non-labelled vitamin B1 from animal tissues (liver, kidney, spleen, muscle) was substituted by the labelled one, the parenterally injected enzyme destroyed up to 30-50% of total thiamine content. Brain and skeletal muscle tissues are more resistant to thiaminase action.
mesh_terms: D019883:Alkyl and Aryl Transferases; D000818:Animals; D002151:Calorimetry; D002250:Carbon Radioisotopes; D004789:Enzyme Activation; D007263:Infusions, Parenteral; D051379:Mice; D008974:Mollusca / Q000201:enzymology; D013831:Thiamine / Q000378:metabolism; D014018:Tissue Distribution; D014166:Transferases / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D014166:Transferases; D019883:Alkyl and Aryl Transferases; C022737:thiamin pyridinylase; D013831:Thiamine
vernacular_title: Priamoe testirovanie antivitaminnogo deistviia tiaminazy, vvodimoĭ v organizm parenteral'no.