Schistosoma mansoni: partial purification and properties of ornithine-delta-transaminase. |
| |
Authors: | M Goldberg E Flescher J Lengy |
| |
Institution: | Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel |
| |
Abstract: | Ornithine-δ-transaminase (OTA) (EC 2.6.1.13) was isolated from Schistosoma mansoni and purified more than 16-fold. Treatment of the worm homogenate with 0.4% deoxycholate (DOC) in the presence of 0.8 M KC1 and 0.15 M NaCl at pH 8.3 resulted in solubilization of 85% of the enzyme. Sonication and high-speed centrifugation were unnecessary. The solubilization procedure and the subsequent purification steps required the presence of the coenzyme pyridoxal phosphate. The optimal pH for OTA was 8.5 and the optimal incubation temperature was 55 C. Michaelis-Menten constants (Km) for ornithine and α-ketoglutarate were 1.53 mM and 2.07 mM, respectively, in enzyme preparations with a specific activity of 22–29 μmoles/hr/mg protein. The enzyme showed a high affinity for α-ketoglutarate but considerably less affinity for oxaloacetate and pyruvate. High concentrations of α-ketoglutarate and ornithine inhibited the OTA activity. Similarly inhibitory were the structurally related amino acids isoleucine and serine and also oxaloacetate. The Km for α-ketoglutarate in the presence of oxaloacetate was 1.3 mM and the Vmax was 8.38 μmoles/hr/mg protein. |
| |
Keywords: | Trematode Blood fluke Ornithine-δ-transaminase (EC 2 6 1 13) solubilization partial purification kinetics and kinetic constants pyridoxal phosphate dependence |
本文献已被 ScienceDirect 等数据库收录! |