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1.
Sakurai Y Shima M Matsumoto T Takatsuka H Nishiya K Kasuda S Fujimura Y Yoshioka A 《Biochimica et biophysica acta》2003,1649(1):51-57
One of haemorrhagic toxins present in snake venoms is L-amino acid oxidase (LAO), which catalyzes the oxidative deamination of L-amino acids with the generation of hydrogen peroxide. Although it is widely accepted that LAO alters platelet function, the effects of LAO on human blood coagulation remain largely unknown. The present study demonstrated, for the first time, that M-LAO, LAO purified from the venom of Agkistrodon halys blomhoffii (Japanese mamushi), possesses an anticoagulant activity. Thrombelastography (TEG) showed that M-LAO significantly delayed the onset and the progress of the coagulation process. In addition, the enzyme prolonged the activated partial thromboplastin time (aPTT) dose-dependently, but had little effect on the prothrombin time (PT), suggesting that its principal activity was mediated in the intrinsic coagulation pathway. Furthermore, M-LAO reduced factor IX procoagulant activity in a dose-dependent manner and did not affect other coagulation factors. These results indicate that M-LAO has an anticoagulant activity that impairs the intrinsic clotting by inhibiting factor IX. 相似文献
2.
An l-amino acid oxidase (Akbu-LAAO) was isolated from the venom of Agkistrodon blomhoffii ussurensis snake using DEAE Sephadex A-50 ion-exchange, Sephadex G-75 gel filtration, and high performance liquid chromatographies. The homogeneity and molecular mass of Akbu-LAAO were analyzed by SDS-PAGE and MALDI-TOF spectrometry. The sequences of ten peptides from Akbu-LAAO were established by HPLC-nESI-MS/MS analysis. Protein sequence alignment indicated that i) that Akbu-LAAO is a new snake venom LAAO, and ii) Akbu-LAAO shares homology with several LAAOs from the venoms of Calloselasma rhodost, Agkistrodon halys, Daboia russellii siamensis, and Trimeresurus stejnegeri. Akbu-LAAO is a homodimer with a molecular mass of ∼124.4 kDa. It reacts optimally with its enzymatic substrate, Leu, at pH 4.7 with a Km of 2.1 mM. ICP-AES measurements showed that Akbu-LAAO contains four Zn2+ per dimer that are unessential for the hydrolytic activity of the enzyme. The emission fluorescence intensity of Akbu-LAAO decreases by 61% on removal of Zn2+ indicating that the zinc probably helps maintain the structural integrity of the enzyme. The addition of exogenous metal ions, including Mg2+, Mn2+, Ca2+, Ce3+, Nd3+, Co2+ and Tb3+, increases the l-Leu hydrolytic activity of the enzyme. Akbu-LAAO shows apparent anti-aggregation effects on human and rabbit platelets. It exhibits a strong bacteriostasis effect on Staphylococcus aureus, eighteen fold that of cephalosporin C under the same conditions. Taken together, the biochemical, proteomic, structural and functional characterizations reveal that Akbu-LAAO is a novel LAAO with promise for biotechnological and medical applications. 相似文献
3.
Gustavo B. Naumann Liliana F. Silva Luciana Silva Gilson Faria Michael Richardson Karla Evangelista Markus Kohlhoff Celia M.F. Gontijo Alexei Navdaev Flavia F. de Rezende Johannes A. Eble Eladio F. Sanchez 《Biochimica et Biophysica Acta (BBA)/General Subjects》2011