PURIFICATION, CHARACTERIZATION STUDIES OF L-GLUTAMINASE FROM ASPERGILLUS FLAVUS STRAIN S4

Abstract

L-glutaminase [EC.3.5.1.2] is an amidohydrolase that catalyzes the hydrolytic deamination of L-glutamine, resulting in the production of L-glutamic acid and ammonia. The L-glutaminase has received a significant attention due to its potential as an anticancer agent. In the present study, soil sample were collected from the Visakhapatnam District, Andhra Pradesh. The aim of this work was to purify L-glutaminase from Aspergillus flavus strain S4. Saturation at 70% ammonium sulphate concentration showed the maximum specific activity (38.22 U/mg protein) with 2.50-fold purification. The purity of the L-glutaminase after DEAE cellulose was increased by 4.56-fold when compared to the crude enzyme. The specific activity and purification fold of the enzyme after DEAE cellulose ion exchange was (69.61 U/mg protein) with a recovery of 37.61%. Molecular weight of L-glutaminase was determined from the standard graph and was found to be 23 kDa. Protein sequencing of the purified enzyme was carried out using MALDI-TOF and the obtained sequence is 204 amino acids in length (21.96 kDa). the results obtained in the present investigation demonstrated that the new fungal strain Aspergillus flavus strain S4 was isolated and identified. The L-glutaminase obtained from this strain showed unique properties like optimum activity at neutral pH (7.0), optimum temperature at 30^oC with great pharmaceutical applications. Low K_M exhibited by this L-glutaminase indicates that it is advantageous as it has greater affinity with the substrate and provides a scope for its use in pharmaceutical sector.