Characteristics of a Cold-Adapted L-glutaminase with Potential Applications in the Food Industry

Abstract

L-glutaminases are enzymes that catalyze the hydrolysis of L-glutamine, producing L-glutamate and ammonium, and they have promising applications in pharmaceutical and food industries. Several investigations have focused on thermotolerant L-glutaminases; however, studies on cold-adapted L-glutaminases have not been reported. These enzymes could be useful in the food industry because they display high catalytic activity at low and room temperatures, a valuable feature in processes aimed to save energy. Besides, they can be easily inactivated by warming and are suitable to prevent decomposition of thermo-labile compounds. The objectives of this work were to characterize the L-glutaminase from the Antarctic bacterium Bizionia argentinensis and analyze its capability as flavor enhancer of protein hydrolysates. The enzyme was heterologously expressed and purified from Escherichia coli, obtaining optimum and homogeneous yields. Kinetic parameters K m and V max were located at the lower and upper range of values reported for L-glutaminases, suggesting high catalytic efficiency. Optimum temperature was 25 °C, and the enzyme conserved around 90% of maximum activity at 0 °C and in presence of 15% (v/v) ethanol and methanol. In saline conditions, the enzyme conserved around 80% of maximum activity in 3 M NaCl. Analysis of structural model suggested cold-adaptation features such as low Arg/ (Arg+Lys) ratio and fewer intramolecular interactions than mesophilic and thermo-tolerant L-glutaminases. This work provides a novel cold-adapted L-glutaminase with promising features in the food industry.

Enhanced salt-tolerance of Bacillus subtilis glutaminase by fusing self-assembling amphipathic peptides at its N-terminus

“…Glutaminase catalyzes the production of L-glutamic acid from L-glutamine, which could improve the umami taste of soy sauce. Due to the high salt content (15–18% NaCl) required by soy sauce fermentation, many studies focused on the screening of salt-tolerant glutaminases from bacteria ( Wakayama et al, 2005 ; Kumar et al, 2012 ; Mosallatpour et al, 2019 ; Ferreira et al, 2021 ) and fungi ( Sato et al, 1999 ; Masuo et al, 2005 ; Elshafei et al, 2014 ). However, there are very few studies on the sat-tolerance enhancement of glutaminase via molecular modification.…”

“…LKG-01 ( Kumar et al, 2012 ), Bacillus amyloliquefaciens ( Ye et al, 2013 ), Cohnella sp. A01 ( Mosallatpour et al, 2019 ), Bizionia argentinensis ( Ferreira et al, 2021 ). Among them, the Cohnella glutaminase retained 90% of the catalytic activity in a 25% NaCl solution ( Mosallatpour et al, 2019 ).…”

Antioxidant potential of L-asparaginase and L-glutaminase excreted by Monascus sp.

“…3.5.1.2; L-glutamine amidohydrolase) performs the hydrolysis of L-glutamine releasing L-glutamate and ammonia. This amidohydrolase has a wide variety of applications, and in the food industry they act in the mitigation of acrylamide (DURTHI et al, 2020), in enhancing the flavor of foods (FERREIRA et al, 2021), in theanine production and food supplementation (SHUAI et al, 2019), in the production of soy based sauces and derivatives (BARZKAR et al, 2021). As a therapeutic application, it has an antiviral (LOUCIF et al, 2021) and antineoplastic (MASISI et al, 2020) effect.…”