The Specific Effects of Buffers Upon Urease Activity

Howell, Stacey F.; Sumner, James B.

doi:10.1016/s0021-9258(18)75737-2

“…In the absence of CS, the pH was observed to increase from 5.5 to 9 at the end of the reaction, while the presence of CS controlled the pH such that it increased from 5.5 to 6.5 (Figure S5a). At elevated pH, Urs activity is expected to be limited, with reports noting that Urs maintains activity from below pH 3 to 7.5 [31, 32] . Importantly, after electrodeposition of a single layer Urs hydrogel , Urs activity remained unchanged compared to the Urs CS,aq case (Figure 2 a, bottom).…”

Section: Resultsmentioning

confidence: 92%

“…At elevated pH, Urs activity is expected to be limited, with reports noting that Urs maintains activity from below pH 3t o7 .5. [31,32] Importantly,a fter electrodeposition of as ingle layer Urs hydrogel ,U rs activity remained unchanged compared to the Urs CS,aq case (Figure 2a,bottom).…”

Section: Resultsmentioning

confidence: 93%

Real‐Time NMR Monitoring of Spatially Segregated Enzymatic Reactions in Multilayered Hydrogel Assemblies**

Nordin

¹

,

Bordonali

²

,

Davoodi

³

et al. 2021

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Compartmentalized chemical reactions at the microscale are important in biotechnology, yet monitoring the molecular content at these small scales is challenging. To address this challenge, we integrate a compact, reconfigurable reaction cell featuring electrochemical functionality with high‐resolution NMR spectroscopy. We demonstrate the operation of this system by monitoring the activity of enzymes immobilized in chemically distinct layers within a multi‐layered chitosan hydrogel assembly. As a benchmark, we observed the parallel activities of urease (Urs), catalase (Cat), and glucose oxidase (GOx) by monitoring reagent and product concentrations in real‐time. Simultaneous monitoring of an independent enzymatic process (Urs) together with a cooperative process (GOx + Cat) was achieved, with chemical conversion modulation of the GOx + Cat process demonstrated by varying the order in which the hydrogel was assembled.

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“…At elevated pH, Urs activity is expected to be limited, with reports noting that Urs maintains activity from below pH 3 to 7.5. [ 31 , 32 ] Importantly, after electrodeposition of a single layer Urs hydrogel , Urs activity remained unchanged compared to the Urs CS,aq case (Figure 2 a , bottom).…”

Section: Resultsmentioning

confidence: 96%

Real‐Time NMR Monitoring of Spatially Segregated Enzymatic Reactions in Multilayered Hydrogel Assemblies**

Nordin

¹

,

Bordonali

²

,

Davoodi

³

et al. 2021

Angew Chem Int Ed

4

0

View full text Add to dashboard Cite

Compartmentalized chemical reactions at the microscale are important in biotechnology, yet monitoring the molecular content at these small scales is challenging. To address this challenge, we integrate a compact, reconfigurable reaction cell featuring electrochemical functionality with high‐resolution NMR spectroscopy. We demonstrate the operation of this system by monitoring the activity of enzymes immobilized in chemically distinct layers within a multi‐layered chitosan hydrogel assembly. As a benchmark, we observed the parallel activities of urease (Urs), catalase (Cat), and glucose oxidase (GOx) by monitoring reagent and product concentrations in real‐time. Simultaneous monitoring of an independent enzymatic process (Urs) together with a cooperative process (GOx + Cat) was achieved, with chemical conversion modulation of the GOx + Cat process demonstrated by varying the order in which the hydrogel was assembled.

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“…(i.e., 7.4), as they have used Tris-HCl to measure pH optima. Howell, S.F., Sumner, and J.B. [ 112 ] have also studied the effect of different buffers on urease activity and concluded that activity of enzyme depends on the type of buffer, temperature, and salt concentration. Similarly, Illanes , Andrés, and others [ 111 , 113 ] have also reported the effects of matrix on pH maxima of different enzyme.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Alginate Nanogels with Polyvalent 3D Transition Metal Cations: Applications in Urease Immobilization

Saxena

¹

,

Sharda

²

,

Kumar

³

et al. 2022

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Biocompatible nanogels are highly in demand and have the potential to be used in various applications, e.g., for the encapsulation of sensitive biomacromolecules. In the present study, we have developed water-in-oil microemulsions of sodium alginate sol/hexane/Span 20 as a template for controlled synthesis of alginate nanogels, cross-linked with 3d transition metal cations (Mn2+, Fe3+, and Co2+). The results suggest that the stable template of 110 nm dimensions can be obtained by microemulsion technique using Span 20 at concentrations of 10mM and above, showing a zeta potential of −57.3 mV. A comparison of the effects of the cross-links on the morphology, surface charge, protein (urease enzyme) encapsulation properties, and stability of the resulting nanogels were studied. Alginate nanogels, cross-linked with Mn2+, Fe3+, or Co2+ did not show any gradation in the hydrodynamic diameter. The shape of alginate nanogels, cross-linked with Mn2+ or Co2+, were spherical; whereas, nanogels cross-linked with Fe3+ (Fe–alginate) were non-spherical and rice-shaped. The zeta potential, enzyme loading efficiency, and enzyme activity of Fe–alginate was the highest among all the nanogels studied. It was found that the morphology of particles influenced the percent immobilization, loading capacity, and loading efficiency of encapsulated enzymes. These particles are promising candidates for biosensing and efficient drug delivery due to their relatively high loading capacity, biocompatibility, easy fabrication, and easy handling.

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The Specific Effects of Buffers Upon Urease Activity

Cited by 69 publications

References 8 publications

Real‐Time NMR Monitoring of Spatially Segregated Enzymatic Reactions in Multilayered Hydrogel Assemblies**

Real‐Time NMR Monitoring of Spatially Segregated Enzymatic Reactions in Multilayered Hydrogel Assemblies**

Real‐Time NMR Monitoring of Spatially Segregated Enzymatic Reactions in Multilayered Hydrogel Assemblies**

Synthesis of Alginate Nanogels with Polyvalent 3D Transition Metal Cations: Applications in Urease Immobilization

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