Mechanisms of aggregation of alpha- and beta-amylases in aqueous dispersions

Liu, Hsuan‐Liang; Chen, Wen-Jang; Chou, Shih-Nung

doi:10.1016/s0927-7765(02)00142-x

Cited by 34 publications

(20 citation statements)

References 30 publications

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“…ScAmy 1 activation by β‐ME could be explained by the reduction of aggregate size by destroying the intermolecular disulfide linkages (Liu et al. 2003) and/or by the protection of thiol groups that stabilize the three dimensional structure of ScAmy 1 protein.…”

Section: Discussionmentioning

confidence: 99%

PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OFSCLEROTINIA SCLEROTIORUMα-AMYLASE ScAmy₁: ASSAY IN STARCH LIQUEFACTION TREATMENTS

Khedher¹,

Bressollier²,

Urdaci³

et al. 2008

Journal of Food Biochemistry

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Among the lytic enzymes secreted by the phytopathogen fungus Sclerotinia sclerotiorum, a starch‐degrading activity has been isolated and characterized. Two extracellular α‐amylases were produced in culture medium in presence of oats flour as carbons sources. An endoamylase named ScAmy1 was purified to homogeneity by ammonium sulfate precipitation, phosphocellulose and cation exchange high performance liquid chromatographies. Molecular mass of purified ScAmy1 was estimated as 54 kDa. Amylase exhibits maximal activity at pH 5 to 6 and at temperature 60C. ScAmy1 was stable in a pH range of (5–11) and at 50C. Initial activity was still conserved 40%, after heating at 60C during 30 min. In addition, Ca2 + activate and stabilize the enzyme. Starch end products were determined as low molecular oligoglucanes, the liquefying power of ScAmy1 was also tested with the Amylograph Brabender, results suggest a suitable application of ScAmy1 in several industrial process. PRACTICAL APPLICATIONS α‐Amylase ScAmy1 was highly produced from Sclerotinia sclerotiorum on oats flour – a cheaper by‐agro‐substrate product. The enzyme was purified and biochemical characterized. ScAmy1 was applied in starch liquefaction treatments assay. The enzyme allows a decrease in peak viscosity after gelatinization and therefore has an important liquefying power. ScAmy1 has a nearly liquefaction effect on flour compared to the commercial enzyme Novamyl, from Novozymes, donated by Novo Nordisk Co. (Denmark). Enzyme end products were analyzed and identified as oligoglucanes and dextrins. Those are widely applied in food, paper, textile and pharmacological industries. Oligosaccharides are useful as prebiotics as dietary fiber or slowly digestible starch derivatives, and they can be used in form of supplement to certain foodstuffs.

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Section: Discussionmentioning

confidence: 99%

PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OFSCLEROTINIA SCLEROTIORUMα-AMYLASE ScAmy₁: ASSAY IN STARCH LIQUEFACTION TREATMENTS

Khedher¹,

Bressollier²,

Urdaci³

et al. 2008

Journal of Food Biochemistry

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“…Moreover, it has been established that, depending on the chemical structure of the protein, the free radicals generated during ultrasonication affect enzymes differently (Liu et al . ). Comparatively, ultrasonication had greater effect on the PPO than on POD of mulberry juice samples at all treatment levels in this work.…”

Section: Resultsmentioning

confidence: 97%

Ultrasonication Treatment Effect on Anthocyanins, Color, Microorganisms and Enzyme Inactivation of Mulberry (M oraceae nigra ) Juice

Engmann

Tchabo

et al. 2014

Journal of Food Processing and Preservation

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This study determined the effect of ultrasonication on anthocyanins, microorganisms, color parameters, polyphenol oxidase and peroxidase activities of mulberry juice. There was more than 4 log10 reduction of total plate count, yeast and mould populations. Ultrasound was found to have significantly (P < 0.05) reduced the amount of anthocyanins, with sample treated at 24 kHz for 30 min, retaining the highest percentage (94.40 ± 0.56%). Relatively, ultrasonication reduced polyphenol oxidase activity to a greater extent as compared with peroxidase activity. Maximum inactivation of polyphenol oxidase activity (45.04%) was achieved at 22 kHz for 10 min. Color brightness was significantly (P < 0.05) increased, as well as the hue and chroma for most of the samples in comparison with the control. The sample treated at 24 kHz for 20 min had the highest values for brightness, hue, chroma and total color difference, respectively as 6.8 ± 0.01, 150.96 ± 1.70, 9.02 ± 0.08 and 9.12 ± 0.13, making it the most conspicuous. PRACTICAL APPLICATIONSThe study demonstrated the use of ultrasound to produce a fresh-like mulberry juice that can serve as a functional food product as essential phytochemicals were preserved, particularly anthocyanins, which have been demonstrated to have therapeutic properties.

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“…The change in molecular size is always one of the most important clues to explore the protein inactivation mechanism (Iyer and Ananthanarayan, 2008; Lencki et al, 1992). Various methods to detect protein size changes have been employed in protein inactivation studies, including dynamic light scattering (Baptista et al, 2003; Liu et al, 2003), analytical ultracentrifugation (Kurganov et al, 2000; Urano et al, 2006), native SDS–PAGE (Kemble and Sun, 2009), etc. In our study, native SDS–PAGE of the inactivated MBP‐HepI gave a dimer band and the band turned darker with the progress of the inactivation (lanes 1–7, Fig.…”

Section: Resultsmentioning

confidence: 99%

Biochemical analysis and kinetic modeling of the thermal inactivation of MBP‐fused heparinase I: Implications for a comprehensive thermostabilization strategy

Chen

et al. 2011

Biotech & Bioengineering

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Enzymatic degradation of heparin by heparin lyases has not only largely facilitated heparin structural analysis and contamination detection, but also showed great potential to be a green and cost-effective way to produce low molecular weight heparin (LMWH). However, the commercial use of heparinase I (HepI), one of the most studied heparin lyases, has been largely hampered by its low productivity and extremely poor thermostability. Here we report the thermal inactivation mechanism and strategic thermal stabilization of maltose-binding protein (MBP)-HepI, a fusion HepI produced in E. coli with high yield, solubility and activity. Biochemical studies demonstrated that the thermal inactivation of MBP-HepI involves an unfolding step that is temperature-dependently reversible, followed by an irreversible dimerization step induced by intermolecular disulfide bonds. A good consistency between the kinetic modeling and experimental data of the inactivation was obtained within a wide range of temperature and enzyme concentration, confirming the adequacy of the proposed inactivation model. Based on the inactivation mechanism, a comprehensive strategy was proposed for the thermal stabilization of MBP-HepI, in which Ca(2+) and Tween 80 were used to inhibit unfolding while site mutation at Cys297 and DTT were employed to suppress dimerization. The engineered enzyme exhibits remarkably improved storage and operational thermostability, for example, 16-fold increase in half-life at its optimum temperature of 30 °C and 8-fold increase in remaining activity of 95% after 1-week storage at 4 °C, and therefore shows great potential as a commercial biocatalyst for heparin degradation in the pharmaceutical industry.

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Mechanisms of aggregation of alpha- and beta-amylases in aqueous dispersions

Cited by 34 publications

References 30 publications

PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OFSCLEROTINIA SCLEROTIORUMα-AMYLASE ScAmy₁: ASSAY IN STARCH LIQUEFACTION TREATMENTS

PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OFSCLEROTINIA SCLEROTIORUMα-AMYLASE ScAmy₁: ASSAY IN STARCH LIQUEFACTION TREATMENTS

Ultrasonication Treatment Effect on Anthocyanins, Color, Microorganisms and Enzyme Inactivation of Mulberry (M oraceae nigra ) Juice

Biochemical analysis and kinetic modeling of the thermal inactivation of MBP‐fused heparinase I: Implications for a comprehensive thermostabilization strategy

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Mechanisms of aggregation of alpha- and beta-amylases in aqueous dispersions

Cited by 34 publications

References 30 publications

PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OFSCLEROTINIA SCLEROTIORUMα-AMYLASE ScAmy1: ASSAY IN STARCH LIQUEFACTION TREATMENTS

PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OFSCLEROTINIA SCLEROTIORUMα-AMYLASE ScAmy1: ASSAY IN STARCH LIQUEFACTION TREATMENTS

Ultrasonication Treatment Effect on Anthocyanins, Color, Microorganisms and Enzyme Inactivation of Mulberry (M oraceae nigra ) Juice

Biochemical analysis and kinetic modeling of the thermal inactivation of MBP‐fused heparinase I: Implications for a comprehensive thermostabilization strategy

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PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OFSCLEROTINIA SCLEROTIORUMα-AMYLASE ScAmy₁: ASSAY IN STARCH LIQUEFACTION TREATMENTS

PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OFSCLEROTINIA SCLEROTIORUMα-AMYLASE ScAmy₁: ASSAY IN STARCH LIQUEFACTION TREATMENTS