A copper reagent for the determination of hexuronic acids and certain ketohexoses

Milner, Yoram; Avigad, Gad

doi:10.1016/s0008-6215(00)80191-3

Cited by 191 publications

(101 citation statements)

References 9 publications

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“…Determination of ␣-Glucuronidase Activity-The ␣-glucuronidase activity was quantified using a colorimetric assay for uronic acids (27). For aldouronic acids, the substrate (6 mg/ml) was incubated with 0.5 M Agu67A in 100 l of citrate buffer (50 4 ) was added for color development.…”

Section: Methodsmentioning

confidence: 99%

Biochemical and Structural Insights into Xylan Utilization by the Thermophilic Bacterium Caldanaerobius polysaccharolyticus

Han

Agarwal

Dodd

et al. 2012

Journal of Biological Chemistry

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Background: Caldanaerobius polysaccharolyticus is a thermophile with a hemicellulose utilization gene cluster. Results: The cluster is induced by xylan. The ligand-binding cleft of XBP1 is optimized for binding xylotriose. Conclusion:This gene cluster encodes all of the proteins required to degrade xylan, transport the fragments, and metabolize them via the pentose-phosphate pathway. Significance: This gene cluster could be designed as a cassette to impart a capacity for utilizing hemicellulose.

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Section: Methodsmentioning

confidence: 99%

Biochemical and Structural Insights into Xylan Utilization by the Thermophilic Bacterium Caldanaerobius polysaccharolyticus

Han

Agarwal

Dodd

et al. 2012

Journal of Biological Chemistry

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“…Heat-denatured samples were used as controls. Reactions were terminated by the addition of copper reagent (Somogyi, 1952) as reformulated for the specific determination of uronic acid reducing groups (Milner and Avigad, 1967). Enzyme activity is expressed as pmol of galacturonic reducing equivalents (g tissue fresh weight)-' h-'.…”

Section: Extraction and Assay Of Pc Activitymentioning

confidence: 99%

Polyuronides in Avocado (Persea americana) and Tomato (Lycopersicon esculentum) Fruits Exhibit Markedly Different Patterns of Molecular Weight Downshifts during Ripening

1993

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Avocado (Persea americana) fruit experience a rapid and extensive loss of firmness during ripening. In this study, we examined whether the chelator solubility and molecular weight of avocado polyuronides paralleled the accumulation of polygalacturonase (PC) activity and loss in fruit firmness. Polyuronides were derived from ethanolic precipitates of avocado mesocarp prepared using a procedure to rapidly inactivate endogenous enzymes. During ripening, chelator (cyclohexane-trans-l,2-diamine tetraacetic acid [CDlA])-soluble polyuronides increased from approximately 30 to 40 pg of galacturonic acid equivalents (mg alcohol-insoluble solids)-' in preripe fruit to 150 to 170 pg mg-' in postclimacteric fruit. In preripe fruit, chelator-extractable polyuronides were of high molecular weight and were partially excluded from Sepharose CL-26-300 gel filtration media. Avocado polyuronides exhibited marked downshifts in molecular weight during ripening. At the postclimacteric stage, nearly all chelator-extractable polyuronides, which constituted from 75 to 90% of total cell wall uronic acid content, eluted near the total volume of the filtration media. Rechromatography of low molecular weight polyuronides on BioCel P-4 disclosed that oligomeric uronic acids are produced in vivo during avocado ripening. l h e gel filtration behavior and pattern of depolymerization of avocado polyuronides were not influenced by the polyuronide extraction protocol (imidazole versus CDTA) or by chromatographic conditions designed to minimize interpolymeric aggregation. Polyuronides from ripening tomato (fycopersicon esculentum) fruit extracted and chromatographed under conditions identical with those used for avocado polyuronides exhibited markedly less rapid and less extensive downshifts in molecular weight during the transition from mature-green to fully ripe. Even during a 9-d period beyond the fully ripe stage, tomato fruit polyuronides exhibited limited additional depolymerization and did not include oligomeric species. A comparison of the data for the avocado and tomato fruit indicates that downshifts in polyuronide molecular weight are a prominent feature of avocado ripening and may also explain why molecular down-regulation of PC (EC 3.2.1.15) in tomato fruit has resulted in minimal effects on fruit performance until the terminal stages of ripening.Avocado fruit soften extensively during ripening, with mesocarp firmness, measured in terms of resistance to penetration, exceeding 450 N at the preripe stage and decreasing severa1 orders of magnitude during ripening (Pesis et al., 1978; Awad and Young, 1979; O'Donoghue and Huber,

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“…As reported by Milner and Avigard (1967), their method was specific for oxidation of hexuronic acid (Table 1). * Percent ratio to xylose in absorbance .…”

Section: Resultsmentioning

confidence: 85%

Reducing terminals and molecular weights of glycosaminoglycans in normal human urine.

Endo

Namiki

Yosizawa

1980

Tohoku J. Exp. Med.

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A copper reagent for the determination of hexuronic acids and certain ketohexoses

Cited by 191 publications

References 9 publications

Biochemical and Structural Insights into Xylan Utilization by the Thermophilic Bacterium Caldanaerobius polysaccharolyticus

Biochemical and Structural Insights into Xylan Utilization by the Thermophilic Bacterium Caldanaerobius polysaccharolyticus

Polyuronides in Avocado (Persea americana) and Tomato (Lycopersicon esculentum) Fruits Exhibit Markedly Different Patterns of Molecular Weight Downshifts during Ripening

Reducing terminals and molecular weights of glycosaminoglycans in normal human urine.

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