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Zhiyan Song Kari J. Parker Idorenyin Enoh Hua Zhao Olarongbe Olubajo 《Analytical and bioanalytical chemistry》2009,395(5):1453-1459
We conducted 31P NMR kinetic studies and 1H-diffusion measurements on myosin-catalyzed hydrolysis of adenosine triphosphate (ATP) under varied conditions. The data
elucidate well the overall hydrolysis rate and various factors that significantly impact the reaction. We found that the enzymatic
hydrolysis of ATP to adenosine diphosphate (ADP) was followed by ADP hydrolysis, and different nucleotides such as ADP and
guanosine triphosphate acted as competitors of ATP. Increasing ATP or Mg2+ concentration resulted in decreased hydrolysis rate, and such effect can be related to the decrease of ATP diffusion constants.
Below 50 °C, the hydrolysis was accelerated by increasing temperature following the Arrhenius’ law, but the hydrolysis rate
was significantly lowered at higher temperature (~60 °C), due to the thermal–denaturation of myosin. The optimal pH range
was around pH 6–8. These results are important for characterization of myosin-catalyzed ATP hydrolysis, and the method is
also applicable to other enzymatic nucleotide reactions. 相似文献
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Zhiyan Song Kari J. Parker Idorenyin Enoh Hua Zhao Olarongbe Olubajo 《Magnetic resonance in chemistry : MRC》2010,48(2):123-128
Interaction of polyamines with nucleotides plays a key role in many biological processes. Here we use multiple NMR techniques to characterize interaction of spermidine with adenosine 5′‐triphosphate (ATP). Two‐dimensional 1H‐15N spectra obtained from gs‐HMBC experiments at varied pH show significant shift of N‐1 peak around pH 2.0–7.0 range, suggesting that spermidine binds to N‐1 site of ATP base. The binding facilitates N‐1 deprotonation, shifting its pKa from 4.3 to 3.4. By correlating 15N and 31P chemical shift data, it is clear that spermidine is capable of concurrently binding to ATP base and phosphate sites around pH 4.0–7.0. The self‐diffusion constants derived from 1H PFG‐diffusion measurements provide evidence that binding of spermidine to ATP is in 1:1 ratio, and pH variations do not induce significant nucleotide self‐association in our samples. 31P spectral analysis suggests that at neutral pH, Mg2+ ion competes with spermidine and shows stronger binding to ATP phosphates. From 31P kinetic measurements of myosin‐catalyzed ATP hydrolysis, it is found that binding of spermidine affects the stability and reactivity of ATP. These NMR results are important for advancing the studies on nucleotide–polyamine interaction and its impact on nucleotide structures and activities under varied conditions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Hua Zhao Zhiyan Song Olarongbe Olubajo Janet V. Cowins 《Applied biochemistry and biotechnology》2010,162(1):13-23
Ionic liquids (ILs) are being explored as solvents for the enzymatic methanolysis of triglycerides. However, most available ILs (especially hydrophobic ones) have poor capability in dissolving lipids, while hydrophilic ILs tend to cause enzyme inactivation. Recently, we synthesized a new type of ether-functionalized ionic liquids (ILs) carrying anions of acetate or formate; they are capable of dissolving a variety of substrates and are also lipase-compatible (Green Chem., 2008, 10, 696–705). In the present study, we carried out the lipase-catalyzed transesterifications of Miglyol® oil 812 and soybean oil in these novel ILs. These ILs are capable of dissolving oils at the reaction temperature (50 °C); meanwhile, lipases maintained high catalytic activities in these media even in high concentrations of methanol (up to 50% v/v). High conversions of Miglyol oil were observed in mixtures of IL and methanol (70/30, v/v) when the reaction was catalyzed by a variety of lipases and different enzyme preparations (free and immobilized), especially with the use of two alkylammonium ILs 2 and 3. The preliminary study on the transesterification of soybean oil in IL/methanol mixtures further confirms the potential of using oil-dissolving and lipase-stabilizing ILs in the efficient production of biodiesels. 相似文献
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Improving the Enzyme Catalytic Efficiency Using Ionic Liquids with Kosmotropic Anions 总被引:1,自引:0,他引:1
The kosmotropicity of cations and anions in ionic liquids has a strong influence on the enzyme catalytic efficiency in aqueous environments. The kosmotropic anion CF3COO^- seemed to activate the protease, and the chaotropic anions tended to destabilize the enzyme. 相似文献
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