en ژنتیک/ بیوتکنولوژی Genetics/ Biotechnology پژوهشي Research <p style="text-align: justify;"><strong>Backgroung and Aims:</strong> L-Asparaginase II is a cornerstone of treatment protocols for acute lymphoblastic leukemia. Only asparaginase II obtained from <em>E. coli</em> K12 and <em>Erwinia chrysanthemi</em> have been used in human as therapeutic drug. The therapeutic effects of asparaginase II from <em>E. coli</em> K12 and <em>Erwinia chrysanthemi</em> is accompanied by side effects. It is desirable to search for other asparaginase II sources with novel properties that could be therapeutic and produce an enzyme with less adverse effects.</p> <p style="text-align: justify;"><strong>Materials and Methods</strong><strong>:</strong> Previously, we performed the <em>in vitro</em> studies, including cloning, sequencing and expression of L-asparaginase II genes (<em>ansB</em>) from <em>Citrobacter freundii</em> 1101, <em>Erwinia chrysanthemi</em> DSM 4610, <em>E. coli</em> BL21 and <em>Klebsiella pneumoniae</em> ATCC 10031. In this article, the obtained results were compared <em>bioinformatically</em>. The nucleotide and amino acid sequence alignments were carried out by ClustalW2. Protein localization and signal peptides were predicted by PSORT and SIG-Pred softwares, respectively. Percentages of hydrophobic and hydrophilic residues were calculated by Genscript software. The physicochemical parameters were computed using Expasy&rsquo;s ProtParam prediction server. The secondary and 3D structures were predicted by SOPMA and the online server Phyre2, respectively. The antigenicity of the asparaginase IIs was predicted using Semi-empirical method.</p> <p><strong>Results:</strong> <em>E. coli</em> BL21 and <em>Citrobacter freundii</em> 1101 had the most similarity in physicochemical parameters and antigenicity with <em>E. coli</em> K12. Also, <em>Erwinia chrysanthemi</em> DSM 4610 had the most similarity in physicochemical parameters and antigenicity with <em>Erwinia chrysanthemi</em>.</p> <p style="text-align: justify;"><strong>Conclusions:</strong> In spite of these similarities with drug types, the potentiality of other low-similar asparaginase IIs should also be determined and compared with drug types.</p> Asparaginase, Bioinformatic, Citrobacter freundii, E. coli, Erwinia chrysanthemi, Klebsiella pneumoniae 123 134 http://ijml.ssu.ac.ir/browse.php?a_code=A-10-1-51&slc_lang=en&sid=1 Khosrow Aghaiypour No Gene-Bank Department, Razi Vaccine and Serum Research Institute (RVSRI), Karaj, Iran. Elham Bahreini Yes Department of Biochemistry, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran. Shiva Jafari No Gene-Bank Department, Razi Vaccine and Serum Research Institute (RVSRI), Karaj, Iran.