N-terminal domain of the beta-propeller phytase of Pseudomonas sp. FB15 plays a role for retention of low-temperature activity and catalytic efficiency

2018 ◽  
Vol 117 ◽  
pp. 84-90 ◽  
Author(s):  
Won Je Jang ◽  
Jong Min Lee ◽  
Hae Dae Park ◽  
Yu Bin Choi ◽  
In-Soo Kong
Keyword(s):  
Low Temperature ◽  
Catalytic Efficiency ◽  
Pseudomonas Sp ◽  
Terminal Domain

scholarly journals Kinetic studies and homology modeling of a dual-substrate linalool/nerolidol synthase from Plectranthus amboinicus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nur Suhanawati Ashaari ◽  
Mohd Hairul Ab. Rahim ◽  
Suriana Sabri ◽  
Kok Song Lai ◽  
Adelene Ai-Lian Song ◽  
...  
Keyword(s):  
Active Site ◽  
Catalytic Efficiency ◽  
Kinetic Studies ◽  
Homology Model ◽  
Biochemical Properties ◽  
Terpene Synthase ◽  
Monoterpene Synthase ◽  
Terminal Domain ◽  
Catalytic Active Site ◽  
Plectranthus Amboinicus

AbstractLinalool and nerolidol are terpene alcohols that occur naturally in many aromatic plants and are commonly used in food and cosmetic industries as flavors and fragrances. In plants, linalool and nerolidol are biosynthesized as a result of respective linalool synthase and nerolidol synthase, or a single linalool/nerolidol synthase. In our previous work, we have isolated a linalool/nerolidol synthase (designated as PamTps1) from a local herbal plant, Plectranthus amboinicus, and successfully demonstrated the production of linalool and nerolidol in an Escherichia coli system. In this work, the biochemical properties of PamTps1 were analyzed, and its 3D homology model with the docking positions of its substrates, geranyl pyrophosphate (C10) and farnesyl pyrophosphate (C15) in the active site were constructed. PamTps1 exhibited the highest enzymatic activity at an optimal pH and temperature of 6.5 and 30 °C, respectively, and in the presence of 20 mM magnesium as a cofactor. The Michaelis–Menten constant (Km) and catalytic efficiency (kcat/Km) values of 16.72 ± 1.32 µM and 9.57 × 10–3 µM−1 s−1, respectively, showed that PamTps1 had a higher binding affinity and specificity for GPP instead of FPP as expected for a monoterpene synthase. The PamTps1 exhibits feature of a class I terpene synthase fold that made up of α-helices architecture with N-terminal domain and catalytic C-terminal domain. Nine aromatic residues (W268, Y272, Y299, F371, Y378, Y379, F447, Y517 and Y523) outlined the hydrophobic walls of the active site cavity, whilst residues from the RRx8W motif, RxR motif, H-α1 and J-K loops formed the active site lid that shielded the highly reactive carbocationic intermediates from the solvents. The dual substrates use by PamTps1 was hypothesized to be possible due to the architecture and residues lining the catalytic site that can accommodate larger substrate (FPP) as demonstrated by the protein modelling and docking analysis. This model serves as a first glimpse into the structural insights of the PamTps1 catalytic active site as a multi-substrate linalool/nerolidol synthase.

scholarly journals Effects of Ribosomes and Intracellular Solutes on Activities and Stabilities of Elongation Factor 2 Proteins from Psychrotolerant and Thermophilic Methanogens

2001 ◽  
Vol 183 (6) ◽  
pp. 1974-1982 ◽  
Author(s):  
Torsten Thomas ◽  
Naresh Kumar ◽  
Ricardo Cavicchioli
Keyword(s):  
Low Temperature ◽  
Growth Temperature ◽  
Elongation Factor ◽  
Thermal Characteristics ◽  
High Growth ◽  
Catalytic Efficiency ◽  
Intrinsic Activity ◽  
Methanosarcina Thermophila ◽  
Elongation Factor 2

ABSTRACT Low-temperature-adapted archaea are abundant in the environment, yet little is known about the thermal adaptation of their proteins. We have previously compared elongation factor 2 (EF-2) proteins from Antarctic (Methanococcoides burtonii) and thermophilic (Methanosarcina thermophila) methanogens and found that theM. burtonii EF-2 had greater intrinsic activity at low temperatures and lower thermal stability at high temperatures (T. Thomas and R. Cavicchioli, J. Bacteriol. 182:1328–1332, 2000). While the gross thermal properties correlated with growth temperature, the activity and stability profiles of the EF-2 proteins did not precisely match the optimal growth temperature of each organism. This indicated that intracellular components may affect the thermal characteristics of the EF-2 proteins, and in this study we examined the effects of ribosomes and intracellular solutes. At a high growth temperature the thermophile produced high levels of potassium glutamate, which, when assayed in vitro with EF-2, retarded thermal unfolding and increased catalytic efficiency. In contrast, for the Antarctic methanogen adaptation to growth at a low temperature did not involve the accumulation of stabilizing organic solutes but appeared to result from an increased affinity of EF-2 for GTP and high levels of EF-2 in the cell relative to its low growth rate. Furthermore, ribosomes greatly stimulated GTPase activity and moderately stabilized both EF-2 proteins. These findings illustrate the different physiological strategies that have evolved in two phylogenetically related but thermally distinct methanogens to enable EF-2 to function satisfactorily.

Structure–performance relationships of MnO2 nanocatalyst for the low-temperature SCR removal of NOX under ammonia

RSC Advances ◽  
2016 ◽  
Vol 6 (60) ◽  
pp. 54926-54937 ◽  
Author(s):  
Yi Li ◽  
Yanping Li ◽  
Yuan Wan ◽  
Sihui Zhan ◽  
Qingxin Guan ◽  
...  
Keyword(s):  
Low Temperature ◽  
Catalytic Efficiency ◽  
Sem And Tem ◽  
Low Temperature Scr

To investigate the corresponding relationship between catalytic efficiency and structure, MnO2 nanomaterials (nanospheres, nanosheets, nanorods) have been prepared successfully, and were thoroughly characterized by SEM and TEM.

Critical Role of a Loop at C-Terminal Domain on the Conformational Stability and Catalytic Efficiency of Chondroitinase ABC I

2015 ◽  
Vol 57 (8) ◽  
pp. 727-734 ◽  
Author(s):  
S. Akram Shirdel ◽  
Khosrow Khalifeh ◽  
Abolfazl Golestani ◽  
Bijan Ranjbar ◽  
Khosro Khajeh
Keyword(s):  
Conformational Stability ◽  
Critical Role ◽  
Catalytic Efficiency ◽  
Chondroitinase Abc ◽  
Terminal Domain

scholarly journals Catalytic Oxidation of Ammonia over Cerium-Modified Copper Aluminium Zinc Mixed Oxides

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6581
Author(s):  
Sylwia Górecka ◽  
Kateřina Pacultová ◽  
Dagmar Fridrichová ◽  
Kamil Górecki ◽  
Tereza Bílková ◽  
...  
Keyword(s):  
Low Temperature ◽  
Metal Oxides ◽  
Catalytic Oxidation ◽  
Catalytic Efficiency ◽  
Composition Analysis ◽  
High Catalytic Activity ◽  
Mixed Metal Oxides ◽  
Mixed Metal ◽  
Selective Catalytic Oxidation ◽  
Oxidation Of Ammonia

Copper-containing mixed metal oxides are one of the most promising catalysts of selective catalytic oxidation of ammonia. These materials are characterized by high catalytic efficiency; however, process selectivity to dinitrogen is still an open challenge. The set of Cu-Zn-Al-O and Ce/Cu-Zn-Al-O mixed metal oxides were tested as catalysts of selective catalytic oxidation of ammonia. At the low-temperature range, from 250 °C up to 350 °C, materials show high catalytic activity and relatively high selectivity to dinitrogen. Samples with the highest Cu loading 12 and 15 mol.% of total cation content were found to be the most active materials. Additional sample modification by wet impregnation of cerium (8 wt.%) improves catalytic efficiency, especially N2 selectivity. The comparison of catalytic tests with results of physicochemical characterization allows connecting the catalysts efficiency with the form and distribution of CuO on the samples’ surface. The bulk-like well-developed phases were associated with sample activity, while the dispersed CuO phases with dinitrogen selectivity. Material characterization included phase composition analysis (X-ray powder diffraction, UV-Vis diffuse reflectance spectroscopy), determination of textural properties (low-temperature N2 sorption, scanning electron microscopy) and sample reducibility analysis (H2 temperature-programmed reduction).

scholarly journals Moritella Cold-Active Dihydrofolate Reductase: Are There Natural Limits to Optimization of Catalytic Efficiency at Low Temperature?

2003 ◽  
Vol 185 (18) ◽  
pp. 5519-5526 ◽  
Author(s):  
Ying Xu ◽  
Georges Feller ◽  
Charles Gerday ◽  
Nicolas Glansdorff
Keyword(s):  
Low Temperature ◽  
Dihydrofolate Reductase ◽  
Thermotoga Maritima ◽  
Catalytic Efficiency ◽  
Metabolic Enzyme ◽  
Psychrophilic Bacterium ◽  
E Coli ◽  
Enthalpy Changes ◽  
Maximum Stability ◽  
Order Of Magnitude

ABSTRACT Adapting metabolic enzymes of microorganisms to low temperature environments may require a difficult compromise between velocity and affinity. We have investigated catalytic efficiency in a key metabolic enzyme (dihydrofolate reductase) of Moritella profunda sp. nov., a strictly psychrophilic bacterium with a maximal growth rate at 2°C or less. The enzyme is monomeric (M r = 18,291), 55% identical to its Escherichia coli counterpart, and displays Tm and denaturation enthalpy changes much lower than E. coli and Thermotoga maritima homologues. Its stability curve indicates a maximum stability above the temperature range of the organism, and predicts cold denaturation below 0°C. At mesophilic temperatures the apparent Km value for dihydrofolate is 50- to 80-fold higher than for E. coli, Lactobacillus casei, and T. maritima dihydrofolate reductases, whereas the apparent Km value for NADPH, though higher, remains in the same order of magnitude. At 5°C these values are not significantly modified. The enzyme is also much less sensitive than its E. coli counterpart to the inhibitors methotrexate and trimethoprim. The catalytic efficiency (k cat /Km ) with respect to dihydrofolate is thus much lower than in the other three bacteria. The higher affinity for NADPH could have been maintained by selection since NADPH assists the release of the product tetrahydrofolate. Dihydrofolate reductase adaptation to low temperature thus appears to have entailed a pronounced trade-off between affinity and catalytic velocity. The kinetic features of this psychrophilic protein suggest that enzyme adaptation to low temperature may be constrained by natural limits to optimization of catalytic efficiency.

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