Screening and Production of Fungal Arginine Degrading Enzymes and Testing Their Effects in Auxotrophic Cancers

The aim of the work: Finding and evaluating fungal arginine-degrading enzymes from various Egyptian soil habitats as anticancer mediators against auxotrophic cancer cells was the goal.
Methods: Fungal cultures that produced enzymes degrading arginine were subcultured on malt agar medium. The enzymes were then readily isolated after expression by salting out with ammonium sulfate and purified using anion exchange resin chromatography. Additionally, the evaluation of their auxotrophic anticancer properties in male rabbit animal models weighing close to 2 kg and several cancer cell lines. In this work, fungal arginine degrading enzymes were generated at pH 6.5, 25 °C, and incubation for three days using mineral arginine agar [MAM] selective medium [developed to select only fungi capable of using arginine as a single metabolic source of carbon and nitrogen].
Results: DNA blotting hybridization analyses identified Aspergillus as the primary fungal genus isolating these enzymes in the current investigation. Aspergillus fumigatus produced arginine decarboxylase and arginine deiminase, while Aspergillus niger was the producer of the L-arginase enzyme. They proved to be powerful anticancer drugs when used against these auxotrophic cancer cells. L-arginine amino acid is converted by arginine deiminase into Citrulline and ammonia. Ornithine and urea are produced from arginine by L-arginase. Extracellular proteins were identified as the enzymes degrading arginine. Based on spectrophotometric measurement of the Citrulline concentration and the ammonia concentration resulting from the hydrolysis of L-arginine by arginine deiminase, arginine deiminase synthesis and activity were examined. Using mass spectrometry and western blot-gel electrophoresis, the molecular masses of fungal L-arginase, arginine deiminase and arginine decarboxylase were determined to be 51 kDa, 53 kDa, and 37 kDa, respectively. L-arginase's Km and Vmax values were 8.63 mmol/l and 7.41 μmol/min, respectively.
Conclusion:  The study presented a unique fungal source of arginine-degrading enzymes from different soil conditions as anticancer mediators.