Modeling and validation of L-asparaginase enzyme, an anticancer agent using the tools of computational biology

Background: The L-Asparaginase is a medically important drug. The L-Asparaginase enzyme, an anticancer agent produced by microorganisms is used for the treatment of patients suffering from lymphoma and leukemia. The L-Asparaginase is economical and its administration is easy when compared to other commercial drugs available in market. Many microbes have been reported to produce the L-Asparaginase.Methods: In the present work the sequence of L-Asparaginase enzyme protein was obtained from the Universal Protein Resource (UNIPROT) server. The sequence of L-Asparaginase was used to generate 3-D model of L-Asparaginase in SWISS MODEL server. The constructed L-Asparaginase model was verified using Ramachandran Plot in PROCHECK server.Results: The FASTA format of L-Asparaginase enzyme of Bacillus subtilis strain 168 was retrieved from UNIPROT server. The FASTA format of L-Asparaginase was submitted to SWISS MODEL and its three-dimensional structural model was developed based on relevant template model. The model structure of L-Asparaginase was validated in PROCHECK server using Ramachandran Plot. The Ramachandran Plot of L-Asparaginase model inferred the reliability of L-Asparaginase structure model developed in SWISS MODEL server.  Conclusions: In the present study computational tools were exploited to develop and validate a potent anticancer drug, L-Asparaginase. Further the modeled L-Asparaginase enzyme protein can be improved using advanced bioinformatics tools and the same improved enzyme can be produced by improving the L-Asparaginase producing microbial strains by site-directed mutagenesis in the corresponding gene.

Molecular Modeling and Docking Studies of Cold Active Lipase from Pseudomonas fluorescens.

Molecular Modeling is essential tool in the drug design process describes the generation, manipulation or representation of 3D structures of the molecules and associated physico-chemical properties while docking predicts the preferred orientation of one molecule to a second when bound to each other to form a stable complex. A cold active lipase producing potential psychrophilic bacteria (GN) was isolated and identified by 16S rRNA molecular studies as Pseudomonas vancouverensis. Lipase gene from closely related species P. fluorescens was investigated for their functional role and in silico characterization using molecular modeling and docking studies. A 3D structure of lipase gene was generated with SWISS-MODEL and Discovery Studio 3.0. The stereochemistry of the constructed model of cold active lipase was subjected to energy minimization and the stereo-chemical quality of the predicted structure was assessed. The superimposition of the template (PDBID: 2Z8X) with predicted structure showed that weighted root mean square deviation of Cα trace between the template and the final refined model was 0.2 Å with a significant Zscore of 8.2 and sequence identity was 80.5%. Three ligands P-Nitrophenol, Acetate ion and Diethyl phosphonate were taken for docking calculation with generated structure. They were interacting on the functional motifs of predicted model. It has been observed that Leu26, Tyr29, Asn31, Asp33, Pro315 and Thr316 residues were involved in hydrogen bonding interactions with selected ligands. So these interacted residues can be used as prominent active binding sites and which was common to the predicted active site. Based on above investigations it has been found that P. vancouverensis lipase protein can play a similar role in lipid metabolic process and triglyceride lipase functional activity as reported for P. fluorescens lipase protein.

Molecular modeling of 2-nitropropane dioxygenase domain of Mycobacterium tuberculosis H37Rv and docking of herbal ligands.

The 3D structure of enoyl reductase (ER) domain generated by the SWISS MODEL server contains the 2-nitropropane dioxygenase (2NPD) structure displaying the TIM barrel fold. Though TIM barrel fold is made up of both main and inserted domains, in our study, we could only predict the structure of the main domain, which had central barrel of eight β-strands surrounded by eight α-helices. Superimposition of the 2NPD region of ER domain of Mycobacterium tuberculosis H37Rv on to the corresponding region of 2UVA_G revealed a good structural alignment between the two, suggesting this template to be a good structural homologue. Among various herbal ligands that were screened as inhibitors, daucosterol was found to bind in closest proximity to the flavin mono nucleotide (FMN) binding site with the lowest docking energy