Kinetic Measurements of Cellulase Activity on Insoluble Substrates Using Disodium 2,2' Bicinchoninate

Johnston, David B.; Shoemaker, Sharon P.; Smith, Gary M.; Whitaker, John R.

doi:10.1111/j.1745-4514.1998.tb00246.x

Cited by 35 publications

(16 citation statements)

References 31 publications

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“…Enzyme activity and protein concentration determinations were made as previously reported in Johnston and Singh (2001) according to Johnston et al (1998), Bradford (1976), and Abe et al (1977. One protease unit was defined as the ∆A 280 of 0.001/min (1-cm light path) at pH 4.5 and 40°C, measured as TCA soluble products using hemoglobin as substrate in the presence of 10 mM cysteine.…”

Section: Methodsmentioning

confidence: 99%

Enzymatic Milling of Corn: Optimization of Soaking, Grinding, and Enzyme Incubation Steps

Johnston

2004

Cereal Chem

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Cereal Chem. 81(5):626-632Enzymatic milling is a modified wet-milling process that uses proteases to significantly reduce the total processing time during corn wet milling and eliminates the need for sulfur dioxide as a processing agent. To optimize the overall enzymatic milling procedure and minimize the amount of enzyme, a series of experiments were done to determine the best first grind parameters and the optimal enzyme additions. The yields for germ, germ quality, and starch recovery were used for evaluation of first grind and enzyme addition, respectively. The specific processing conditions evaluated were the soaking time and first grind parameters. After soaking and first grind optimization, enzyme concentration and pH determinations were evaluated using bromelain as an example. The first grind procedure was optimized by evaluating a combination of different soaking and grinding conditions followed by a fixed enzyme addition and incubation step. The pH profile of bromelain for enzymatic milling was evaluated for pH 3.5-6.5 and the optimum was determined to be pH 5.0. Enzyme addition was then evaluated using the optimized first grind conditions and bromelain additions with 0-1.9 g of enzyme (based on protein)/kg of corn. Results showed that the minimum addition of bromelain to reach starch yields equivalent to conventional yields were ≈0.4 g of protein/kg of corn. This amount is significantly less than what was previously used and reported. 2 Corresponding

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Section: Methodsmentioning

confidence: 99%

Enzymatic Milling of Corn: Optimization of Soaking, Grinding, and Enzyme Incubation Steps

Johnston

2004

Cereal Chem

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“…Amylase and native starch hydrolytic activities in the enzyme preparations were measured (Table I). Activity units were defined as the change in the reducing groups, equivalent to an increase in 1 mg of sugar/min, measured using the BCA assay method (Johnston et al 1998). The cellulase, xylanase, and b-glucanase assays used carboxymethyl cellulose, oat spelt xylan, and barley b-glucan, respectively.…”

Section: Methodsmentioning

confidence: 99%

Pasting Properties and Surface Characteristics of Starch Obtained from an Enzymatic Corn Wet‐Milling Process

Johnston

2002

Cereal Chem

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Recently, we reported the development of an enzymatic corn wet‐milling process that reduces or eliminates sulfur dioxide requirements during steeping, considerably reduces steep time, and produces starch yields comparable to that of conventional corn wet‐milling. The best results so far, using the enzymatic corn wet‐milling procedure, were achieved when a particular protease enzyme (bromelain) was used. In this study, pasting properties and surface characteristics of starch obtained from six different enzyme treatments (three glycosidases [β‐glucanase, cellulase, and xylanase] and three proteases [pepsin, acid protease, and bromelain]) using the enzymatic corn wet‐milling procedure were evaluated and compared with those from starch obtained using the conventional corn wet‐milling procedure. Significant effects from enzymatic milling were observed on all the three starch pasting properties (peak, shear thinning, and setback). The setback viscosities of starch from all enzyme treatments were significantly lower compared with those of the control sample, indicating that starch polymers from enzymatic corn wet‐milling do not reassociate to the same extent as with the control. Comparison between bromelain treatment and the control sample showed that starch samples obtained from bromelain treatment are very similar to control starch in water‐binding capacity, molecular breakdown, and time to swell when cooked in water. Significant effects from enzymatic milling were observed on the surface characteristics of starch granules. The glycosidase treatments, especially the β‐glucanase samples, showed holes in the starch granules. No visual differences were observed in starch granules between bromelain and control samples.

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“…Details of preparation of the microemulsion were described earlier [29][30][31]. n = 1-glucose, n = 2-maltose, n = 3-maltotriose, n = 4-maltotetrose, n = 5-maltopentose, n = 7-maltoheptaose, and average n = 7.55-maltodextrin (provided by manufacturer and confirmed with bicinchoninic acid (BCA) assay [32,33]). …”

Section: Methods 1 In Hydrolysis Of Oligomers and Polymersmentioning

confidence: 99%

Ultrasonic Monitoring of Biocatalysis in Solutions and Complex Dispersions

Buckin

Altas

2017

Catalysts

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Abstract:The rapidly growing field of chemical catalysis is dependent on analytical methods for non-destructive real-time monitoring of chemical reactions in complex systems such as emulsions, suspensions and gels, where most analytical techniques are limited in their applicability, especially if the media is opaque, or if the reactants/products do not possess optical activity. High-resolution ultrasonic spectroscopy is one of the novel technologies based on measurements of parameters of ultrasonic waves propagating through analyzed samples, which can be utilized for real-time non-invasive monitoring of chemical reactions. It does not require optical transparency, optical markers and is applicable for monitoring of reactions in continuous media and in micro/nano bioreactors (e.g., nanodroplets of microemulsions). The technology enables measurements of concentrations of substrates and products over the whole course of reaction, analysis of time profiles of the degree of polymerization and molar mass of polymers and oligomers, evolutions of reaction rates, evaluation of kinetic mechanisms, measurements of kinetic and equilibrium constants and reaction Gibbs energy. It also provides tools for assessments of various aspects of performance of catalysts/enzymes including inhibition effects, reversible and irreversible thermal deactivation. In addition, ultrasonic scattering effects in dispersions allow real-time monitoring of structural changes in the medium accompanying chemical reactions.

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Kinetic Measurements of Cellulase Activity on Insoluble Substrates Using Disodium 2,2' Bicinchoninate

Cited by 35 publications

References 31 publications

Enzymatic Milling of Corn: Optimization of Soaking, Grinding, and Enzyme Incubation Steps

Enzymatic Milling of Corn: Optimization of Soaking, Grinding, and Enzyme Incubation Steps

Pasting Properties and Surface Characteristics of Starch Obtained from an Enzymatic Corn Wet‐Milling Process

Ultrasonic Monitoring of Biocatalysis in Solutions and Complex Dispersions

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