l-asparaginase
is an enzyme catalyzing the hydrolysis
of l-asparagine into l-aspartate and ammonia, which
is of great therapeutic importance in tumor treatment. However, commercially
available enzymes are associated with adverse effects, and searching
for a new l-asparaginase with better pharmaceutical properties
was the aim of this work. The coding sequence for Mycobacterium
smegmatis
l-asparaginase (MsA) was cloned
and expressed. The recombinant protein showed high activity toward l-asparagine, whereas none was detected for l-glutamine.
The enzymatic properties (K
m = 1.403 ±
0.24 mM and k
cat = 708.1 ± 25.05
s–1) indicate that the enzyme would be functional
within the expected blood l-asparagine concentration, with
good activity, as shown by k
cat. The pH
and temperature profiles suggest its use as a biopharmaceutical in
humans. Molecular dynamics analysis of the MsA model reveals the formation
of a hydrogen bond network involving catalytic residues with l-asparagine. However, the same is not observed with l-glutamine,
mainly due to steric hindrance. Additionally, the structural feature
of residue 119 being a serine rather than a proline has significant
implications. These findings help explain the low glutaminase activity
observed in MsA, like what is described for the Wolinella
succinogenes enzyme. This establishes mycobacterial
asparaginases as key scaffolds to develop biopharmaceuticals against
acute lymphocytic leukemia.