Microbial L-Asparaginase: A Potent Antitumour Enzyme

184-194L-asparaginase (LA) can be effectively used for the treatment of acute lymphoblastic leukemia and tumour cells. Interest in this enzyme arose few decades ago when it was discovered that the antilymphoma activity of the guinea pig serum was due to LA. For pharmacological and clinical tests, microbial sources are best for the bulk production of LA. Initially this drug failed to fall in antineoplastic category due to the immunogenic reactions caused by the foreign protein. With the development of protein engineering, modifications carried out in purified LA either reduced or completely eliminated the immunogenicity of LA in test model. The improved therapeutic activity and decreased immunogenicity of LA can be of immense use as an antineoplastic agent

Nature of correlated polaron hopping mechanism in A-site cation disorder Nd0.7−xLaxSr0.3MnO3 (x = 0.0, 0.1, 0.2 and 0.3) manganites

The structural, transport and magnetic properties of Nd0.7−xLaxSr0.3MnO3 (for x = 0.0, 0.1, 0.2, 0.3) manganite prepared by solid-state route were investigated. All the samples are exhibiting distorted orthorhombic perovskite structure. Lattice parameters and bond angles are increasing with an increase in La concentration. The electrical resistivity ρ(T → 0) and ρ(Tc), both are decreasing with substitution of La (x = 0.0, 0.1, 0.2, 0.3) and the presence of an external magnetic field giving rise to the colossal magnetoresistance (CMR) effect. The temperature-dependent transport nature has been explored with a correlated polaron hopping mechanism based on the Holstein Hamiltonian model. This model is very well concurring with our experimental results and it is further addressing the widely known transition from the low-temperature metallic to the localized polaron hopping conductivity at high temperature. Furthermore, the spin-order temperature (Tc) and the atomic-order temperature (Tca) both are increasing with La substitution. The present analysis shows that the correlated polaron hopping model describes the transport properties of La-substituted Nd0.7−xLaxSr0.3MnO3 samples