RESUMO
Bacterial L-asparaginases, which are widely used in the antitumor therapy, act only as homotetramers, because their active sites are located at the interface between the subunits of the enzyme. Since salt bridges substantially stabilize L-asparaginase tetramers, we have supposed that oligomerization of bacterial L-asparaginase is a high-avidity process. This assumption was proved by bioinformatic and biosensoric methods. It was shown, that a stable tetrameric complex can be formed only by the subunits of the same L-asparaginase. Using two mutants of L-asparaginase Helicobacter pylori it was shown that specificity of molecular recognition is significantly reduced even by single point mutation at the interface of high-homologous closely-related subunits.
Assuntos
Asparaginase/química , Multimerização Proteica , Sequência de Aminoácidos , Escherichia coli/enzimologia , Helicobacter pylori/enzimologia , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos , Ressonância de Plasmônio de Superfície/métodos , TermodinâmicaRESUMO
The feasibility of obtaining a conjugated benz(a)pyrene-protein antigen in the liver cytochrome P-450 system was studied. Covalent binding of benz(a)pyrene (BP) to albumin was performed with the use of liver microsomal fractions of 3-methylcholanthrene-induced rabbits. It was demonstrated that BP oxidation in liver microsomes is accompanied by covalent binding of [14C]BP to exogenous rabbit albumin. Immunization of rabbits with the obtained conjugate results in the development of a specific immune response to BP, and the appearance of specific antibodies and lymphocytes specifically binding [14C]BP in the blood.
