Cacti as low-cost substrates to produce L-asparaginase by endophytic fungi.

This study aimed to select endophytic fungi to produce L-asparaginase and partially optimising the production of the enzyme using cacti as substrate. Seventeen endophytes were assessed for intracellular enzymatic potential in modified Czapek Dox's medium using L-proline as an inducer. The best producer was evaluated for intracellular and extracellular enzymatic activity in modified Czapek Dox's medium using flours of Opuntia ficus-indica and Nopalea cochenillifera as substrate. The biomass and L-asparaginase production profile was analysed and the best conditions for enzyme production were verified using factorial design. Penicillium decaturense URM 7966, Diaporthe ueckerae URM 8321, and Colletotrichum annellatum URM 8538 produced 0.76 U g- 1, 0.87 U g- 1, and 0.74 U g- 1 L-asparaginase, respectively. Diaporthe ueckerae URM 8321 produced only intracellular L-asparaginase, using flours of N. cochenillifera (0.72 U g- 1) and O. ficus-indica (0.90 U g- 1) and the last was selected for the next steps. The ideal time for biomass and L-asparaginase production was 120 h. The best conditions for enzyme production (1.67 U g- 1) were initial pH 4.0, inoculum concentration 1% and cacti flour concentration 0.2%; where was observed an increase of 46.11% in compared to the initial production. Opuntia ficus-indica flour is indicated as an alternative low-cost substrate for the production of L-asparaginase by the endophytic fungus D. ueckerae URM 8321.

Microbial cell disruption methods for efficient release of enzyme L-asparaginase.

The efficacy of a simple laboratory method for cell disruption based on the glass bead stirring, sonication, osmotic shock, freezing and grinding, or use of solvents and detergents was assessed in this study, via measurements of the release of total protein and L-asparaginase activity. Three different microbial sources of L-asparaginase were used: Escherichia coli BL21 (DE3), Leucosporidium muscorum, and Aspergillus terreus (CCT 7693). This study adjusted and identified the best procedure for each kind of microorganism. Sonication and glass bead stirring led to obtaining filamentous fungus cell-free extracts containing high concentrations of soluble proteins and specific activity; however, sonication was the best since it obtained 4.61 ± 0.12 IU mg-1 after 3 min of operation time. Mechanical methods were also the most effective for yeast cell disruption, but sonication was the technique which yielded a higher efficiency releasing 7.3 IUtotal compared to glass bead stirring releasing 2.7 IUtotal at the same operation time. For bacterium, sonication proved to be the best procedure due to getting the highest specific activity (9.01 IU mg-1) and total enzyme activity (61.7 IU). The data presented lead to conclude that the mechanical methods appeared to be the most effective for the disintegration of the all microbial cells studies. This is the first report related to the experimental comparison of L-ASNase extraction procedures from different microorganisms, which can also be used for extracting periplasm located enzymes from other organisms.

Critical overview of the main features and techniques used for the evaluation of the clinical applicability of L-asparaginase as a biopharmaceutical to treat blood cancer.

L-asparaginase is an enzyme used as a biopharmaceutical to treat acute lymphoblastic leukemia. Several adverse effects have been related to L-asparaginase use, so the scientific community has searched for novel proteoforms of L-ASNase. However, some critical characteristics must be considered for a novel L-ASNase source to be effective as an antitumour drug. Accordingly, this article provides a critical analysis of the parameters and methods applied to estimate L-ASNase concentration, measure the L-ASNase and GLNase activities and kinetics, evaluate the enzyme preparations purity and define the antitumour activity against leukemic cells in vitro. Among the main features, the proposed new enzyme needs to present high affinity for L-asparagine; low percentage of glutaminase activity in relation to L-ASNase; high enzyme stability and half-life and mainly antileukemic activity when a low protein amount is applied. These parameters are discussed in an attempt to guide the consideration of an enzyme as a promising biopharmaceutical against ALL.

Improved pharmacokinetic characteristics and bioactive effects of anticancer enzyme delivery systems.

INTRODUCTION: Anticancer enzymes play important roles in cancer treatment. The anticancer enzyme has been in clinical use to treat acute lymphoblastic leukemia for many years. Other types of anticancer enzymes have been investigated in laboratory studies and clinical trials. Area covered: This paper will provide perspectives on the indications, anticancer mechanisms, enzymatic characteristics (such as molecular weight, organism source, and kinetic parameters) and pharmacokinetic behaviors of anticancer enzymes and their delivery systems by systematically analyzing available literature. The pharmacodynamics of anticancer enzyme delivery systems has also been summarized. Expert opinion: Anticancer enzymes kill cancer cells by depleting important nutrients required for growth or producing metabolite toxic to tumor cells. Suitable enzyme delivery systems have demonstrated promising effects on the pharmacokinetics, bioactivity and application of anticancer enzymes. Their current limitations and future potential are analyzed.[Figure: see text].