Purification and characterization of glutaminase-free L-asparaginase from Pectobacterium carotovorum MTCC 1428.
An intracellular glutaminase-free L-asparaginase from Pectobacterium carotovorum MTCC 1428 was isolated to apparent homogeneity. The homotetramer enzyme has a molecular mass of 144.4 kDa (MALDI-TOF MS) and an isoelectric point of approximately 8.4. The enzyme is very specific for its natural substrate, L-asparagine. The activity of L-asparaginase is activated by mono cations and various effectors including Na+, K+, L-cystine, L-histidine, glutathione and 2-mercaptoethanol whereas it is moderately inhibited by various divalent cations and thiol group blocking reagents. Kinetic parameters, Km, Vmax and kcat of purified L-asparaginase from P. carotovorum MTCC 1428 were found to be 0.657 mM, 4.45 U μg(-1) and 2.751×10(3) s(-1), respectively. Optimum pH of purified L-asparaginase for the hydrolysis of L-asparagine was in the range of 8.0-10.0, and its optimum temperature was found to be 40 °C. The purified L-asparaginase has no partial glutaminase activity, which can reduce the possibility of side effects during the course of anti-cancer therapy.
Kumar
Sanjay
S
Biochemical Engineering Laboratory, Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
Venkata Dasu
V
V
Pakshirajan
K
K
D000595:Amino Acid Sequence; D001215:Asparaginase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D004795:Enzyme Stability; D005972:Glutaminase / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016973:Pectobacterium carotovorum / Q000201:enzymology*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D013379:Substrate Specificity; D013696:Temperature
D001215:Asparaginase; D005972:Glutaminase