Temperature stability: The L-asparaginase enzymes from various sources have different temperature stabilities
ranging from 37⁰C to upto 80⁰C due to differences in their amino acid sequences and structures. Both the wild type and
mutant L-asparaginase enzyme D178P from Escherichia coli remain stable at 37⁰C upto 4 h but after that the wild type
enzyme rapidly loses its residual activity as compared to mutant one. After 6 h incubation, wild type shows 35% while
mutant enzyme shows 19 % loss of activity. With incubation time of 1h, 97% of the mutant and 79% of the wild type
enzyme activity remained at 45⁰C while upto 50⁰C, 90% of mutant and 71 % of the wild type enzyme activity
remained [120]. Zhang and others [115] reported that the immobilized L-asparaginase enzyme showed significantly
higher stability upto 40-50⁰C while loses 70 % of activity at 60⁰C for 30 min and become completely inactivated when
incubated at 80⁰C for 30 min. The enzyme from Cylindrocarpon obtusisporum remains stable at 37⁰C for 30 min while
loses 20% of its activity at 40⁰C [76]. The enzyme from Pseudomonas stutzeri remain stable at 40⁰C for 1h with no
significant loss of activity while have a half-life of 25 min and 10 min at 60⁰C and 65⁰C respectively [54]. Kotzia and
others [50] reported that the Tm of wild type enzyme of Erwinia chrysanthemi and its thermostable variant containing a
single point mutation (Asp133Val) were 46.4⁰C and 55.8⁰C and the half-life of both wild type and mutant enzyme were
found to be 2.7 h and 159.7 h respectively. The enzyme isolated from Helicobacter pylori remained absolutely stable
upto a temperature of 50⁰C for 10 min. But at 53⁰C, after 10 min loses 50% of its activity [109]. L-Asparaginase
obtained from Azatobacter vinelandii remained stable up to a temperature of 50⁰C but get inactivated at 65⁰C [121].
The enzyme of Streptomyces gulbargensis retained its 55% of activity at 80⁰C for 1h at alkaline pH [65].