Bacterial L-asparaginase catalyzes the hydrolysis of L-asparagine to L-aspartic acid. It is normally used as an antineoplastic drug applied in lymphoblastic leukemia chemotherapy and as a food processing aid in baked or fried food industry to inhibit the formation of acrylamide. The present study demonstrates cloning, expression, and characterization of a thermostable L-asparaginase from Thermococcus zilligii AN1 TziAN1_1 and also evaluates the potential for enzymatic acrylamide mitigation in French fries using this enzyme. The recombinant L-asparaginase was purified to homogeneity by nickel-affinity chromatography. The purified enzyme displayed the maximum activity at pH 8.5 and 90 °C, and the optimum temperature was the highest ever reported. The K m, k cat, and k cat/K m values toward L-asparagine were measured to be 6.08 mM, 3267 s(-1), and 537.3 mM(-1) s(-1), respectively. The enzyme retained 70 % of its original activity after 2 h of incubation at 85 °C. When potato samples were treated with 10 U/mL of L-asparaginase at 80 °C for only 4 min, the acrylamide content in final French fries was reduced by 80.5 % compared with the untreated control. Results of this study revealed that the enzyme was highly active at elevated temperatures, reflecting the potential of the T. zilligii L-asparaginase in the food processing industry.

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L-Asparaginases (EC 3.5.1.1) are enzymes that catalyze the hydrolysis of L-asparagine to L-aspartic acid and found in a variety of organisms from microorganisms to mammals. However, they are mainly expressed and produced by microorganisms. Microbial L-asparaginases have received sustained attention due to their irreplaceable role in the therapy of acute lymphoblastic leukemia and for their inhibition of acrylamide formation during food processing. In this article, we review the application of microbial L-asparaginases in medical treatments and acrylamide mitigation. In addition, we describe in detail recent advances in the existing sources, purification, production, properties, molecular modification, and immobilization of L-asparaginase.

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Compared with crystallized TiO 2 , amorphous Nb 2 O 5 has been applied in planar perovskite solar cell as electron transportation layer because of its excellent optical transmittance, low temperature preparation process, and similar Femi level with TiO 2 . However, the electron transfer rate is still limited by its low electron mobility and surface defect via room-temperature deposition process. Herein, a novel double buffer layer of [6,6]-phenyl-C61-butyric acid methyl ester(PCBM)/ionic liquid([EMIM]PF 6 ) has been inserted between perovskite and Nb 2 O 5 film. The PCBM could passive the surface of Nb 2 O 5 and improve electron extraction ability. The insert of [EMIM]PF 6 could improve the hydrophilic of PCBM and decrease the dissolution of PCBM in DMF during spin-coat perovskite precursor solution. A relatively high open voltage (over 1.09 V) and conversion efficiency of 18.8% have been achieved by using a double buffer layer which is the highest PCE of Nb 2 O 5 based perovskite solar cell to our best knowledge. The results indicate room temperature deposited Nb 2 O 5 can be a suitable candidate for replacing crystallized TiO 2 film and proposed modification strategy could facilitate the future development of interface modified layer for high efficient planar perovskite solar cell.

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