ABSTRACT
An extracellular L-glutamate oxidase (GLOD) was purified from soil-isolated Streptomyces sp 18G. The enzyme had a molecular weight of approximately 120,000 and consisted of two identical subunits, each with a molecular weight of 61,000. The isoelectric point was pH 8.5 and the enzyme had an optimal pH between 7.0-7.4. GLOD showed the maximum activity at 37ºC. The GLOD activity was stable at pH ranging from 6.5 to 7.0 for 1 hr. Among 21 amino acids tested for substrate specificity, L-glutamate was almost exclusively oxidized. D-glutamate and L-aspartate were oxidized but only to extents of 0.79 percent and 0.53 percent, respectively.
Subject(s)
Amino Acid Oxidoreductases/isolation & purification , Amino Acid Oxidoreductases/metabolism , Amino Acid Oxidoreductases/chemistry , Streptomyces/enzymology , Chromatography , Culture Media , Hydrogen-Ion Concentration , Isoelectric Point , Molecular Weight , Substrate Specificity , TemperatureABSTRACT
L-amino-acid oxidase(L-AO) form the venom of Lachesi muta muta was purified 72 times (38%) by gel filtration on Sephadex G-100, followed by ion exchange chromatography on DEAE-cellulose and gel filtration on Sephacryl S-300. The protein was shown to be homogeneous by polyacrylamide gel electroforesis, immunoelectrophoresis, immunodiffusion and isoelectric focusing. Its specific activity was 44.4 units/mg protein, using 7.5 mM L-leucine as substrate a nd O-dianisidine as electron donor,at pH 7.6 and 25§C. The increase in absorbance at 436 nm was recorded. The enzyme was characterized as a glycoprotein with an S20,w=6.72,MW=138,000 and pI=5.2. It presented maxima at 389 and 460 nm and contained 2 mol of FAD per mole protein