Purification, characterization and mass spectrometric sequencing of transaldolase from Fusarium oxysporum

Transaldolase (FoTal) was purified to homogeneity from the fungus Fusarium oxysporum. The native enzyme revealed a monomeric structure with molecular mass of 36 kDa. This FoTal depicted an optimal pH of 7.5 using imidazole buffer, while loss of activity was observed with Tris/HCl buffer. The optimal temperature was between 40 and 45 °C and the enzyme became unstable at temperatures above 50 °C. The isoelectric point of the purified enzyme was 4.5. The kinetics of the purified enzyme is consistent with a Ping Pong mechanism. The Km values for d-erythrose-4-phosphate and d-fructose-6-phosphate were 0.49 and 6.66 mM, while the kcat values were estimated at 4114 and 4151 min−1, respectively. LC–MS/MS analysis provided peptide mass and sequence information that facilitated primary structure confirmation, allowing us to identify the FoTal gene (foxg_03074) from the genome of F. oxysporum.