RESUMEN
The exploration of new sources of L-asparaginase with low glutaminase activity is of great interest in both medical and food applications. In the current study, a novel L-asparaginase gene (CobAsnase) from halotolerant Cobetia amphilecti AMI6 was cloned and over-expressed in Escherichia coli. The enzyme had a molecular mass of 37 kDa on SDS-PAGE and dynamic light scattering (DLS) analysis revealed that CobAsnase is a homotetramer in solution. The purified enzyme showed optimum activity at pH and temperature of 7 and 60 °C, respectively, with obvious thermal stability. It exhibited strict substrate specificity towards L-asparagine with no detectable activity on L-glutamine. Pre-treatment of potato slices by CobAsnase prior to frying reduced the acrylamide contents in the processed chips up to 81% compared with untreated control. These results suggest that CobAsnase is a potential candidate for applications in the food industry for mitigation of acrylamide formation in fried potato and baked foods.
Asunto(s)
Asparaginasa/química , Asparaginasa/genética , Glutaminasa/metabolismo , Halomonadaceae/enzimología , Modelos Moleculares , Acrilamida/análisis , Secuencia de Aminoácidos , Clonación Molecular , Simulación por Computador , Cinética , Filogenia , Solanum tuberosum/química , Especificidad por SustratoRESUMEN
N-Acylhomoserine lactonase degrades the lactone ring of N-acylhomoserine lactones (AHLs) and has been widely suggested as a promising candidate for use in bacterial disease control. While a number of AHL lactonases have been characterized, none of them has been developed as a commercially available enzymatic product for in vitro AHL quenching due to their low stability. In this study, a highly stable AHL lactonase (AhlX) was identified and isolated from the marine bacterium Salinicola salaria MCCC1A01339. AhlX is encoded by a 768-bp gene and has a predicted molecular mass of 29 kDa. The enzyme retained approximately 97% activity after incubating at 25 °C for 12 days and ~100% activity after incubating at 60 °C for 2 h. Furthermore, AhlX exhibited a high salt tolerance, retaining approximately 60% of its activity observed in the presence of 25% NaCl. In addition, an AhlX powder made by an industrial spray-drying process attenuated Erwinia carotovora infection. These results suggest that AhlX has great potential for use as an in vitro preventive and therapeutic agent for bacterial diseases.