B lymphoblastic leukemia (B-LL) is a clonal hematopoietic stem cell neoplasm derived from B-cell progenitors, which mainly occurs in children and adolescents and is one of the main causes of death from malignant tumors in this population. The surface marker CD19 is specifically expressed on the membrane of most malignant B-cells, which is widely used as a marker of B-LL antigen-specific immunotherapy. In this study, mesoporous titanium dioxide nanoparticles (MTNs)-based antibody drug delivery system was designed for B-LL treatment. Anti-CD19 monoclonal antibody was conjugated to PEGylated MTNs, and doxorubicin (DOX) was loaded in the nanoparticle. The CD19-PEG-MTN/DOX nanoparticle could recognize CD19 + B-LL cell lines and induced them apoptosis, but nontoxic for the normal cells. Further, after treated with CD19-PEG-MTN/ DOX nanoparticle, pro-apoptotic proteins Bax and Caspase-3 in KOPN 8 and NALM-6 cells were significantly upregulated, but anti-apoptotic proteins Bcl2, MCL-1, HSP 70, and BAG 3 were downregulated, which indicated the activation of the apoptosis pathway by the nanodrug. By contrast, CD19-PEG-MTN/DOX didn't play a part on CD19 À cell line U937. Besides, the cytotoxicity of CD19-PEG-MTN/DOX was low with good biocompatibility. Collectively, CD19-PEG-MTN/DOX is a promising antitumor nanodrug for the treatment of B-LL.
Nitrile hydratase (NHase, EC 4.2.1.84) is an excellent biocatalyst that catalyzes the hydration of nitrile substances to their corresponding amides. Given its catalytic specificity and eco-friendliness, NHase has extensive applications in the chemical, pharmaceutical, and cosmetic industries. To improve the affinity between Rhodococcus erythropolis CCM2595-derived NHase ( ReNHase) and adiponitrile, this study used a semirational design to improve the efficiency of ReNHase in catalyzing the generation of 5-cyanopentanamide from adiponitrile. Enzyme kinetics analysis showed that Km of the mutant ReNHaseB:G196Y was 3.265 mmol l−1, which was lower than that of the wild-type NHase. The affinity of the mutant ReNHaseB:G196Y to adiponitrile was increased by 36.35%, and the efficiency of the mutant ReNHaseB:G196Y in catalyzing adiponitrile to 5-cyanopentamide was increased by 10.11%. The analysis of the enzyme-substrate interaction showed that the hydrogen bond length of the mutant ReNHaseB:G196Y to adiponitrile was shortened by 0.59 Å, which enhanced the interaction between the mutant and adiponitrile and, thereby, increased the substrate affinity. Similarly, the structural analysis showed that the amino acid flexibility near the mutation site of ReNHaseB:G196Y was increased, which enhanced the binding force between the enzyme and adiponitrile. Our work may provide a new theoretical basis for the modification of substrate affinity of NHase and increase the possibility of industrial applications of the enzyme.
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