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4 results on '"Bignasca A"'

1. Using proteolytic enzymes to assess metal bioaccessibility in marine sediments

Author

Paola Rivaro, Antonello Bignasca, Carmela Ianni, and Emanuele Magi

Subjects
chemistry.chemical_classification, Geologic Sediments, Chromatography, biology, Extraction (chemistry), Solid Phase Extraction, Proteolytic enzymes, Proteinase K, Trypsin, Pepsin A, Analytical Chemistry, Acetic acid, chemistry.chemical_compound, Enzyme, chemistry, Pepsin, Metals, Enzymatic hydrolysis, Environmental chemistry, biology.protein, medicine, medicine.drug, Environmental Monitoring, Peptide Hydrolases
Abstract

In this work we tested two proteolytic enzymes (trypsin and pepsin) to evaluate metal bioaccessibility in marine sediments. Some working conditions were studied, in particular incubation time, enzyme concentration and solution/solid ratio, and metals release mechanisms were investigated using both untreated and denatured enzymes. The results obtained with trypsin and pepsin were compared with each other and with results from proteinase K extraction, carried out on the same sediment samples, following a procedure reported in the literature. Moreover, a comparison with the first step of BCR sequential procedure was made. Metal orders of mobility determined with the different enzymes and with acetic acid were compared with the one defined by the enrichment factors in the gut fluids of deposit-feeder organisms. The overall picture suggests that proteinase K has a better capability of reproducing natural phenomena and is therefore more suitable to determine metal bioaccessibility in marine sediments, when the target of the investigation is deposit-feeder organisms.

Published
2011

2. Metal bioavailability in marine sediments measured by chemical extraction and enzymatic mobilisation

Author

Antonello Bignasca, Paola Rivaro, Carmela Ianni, and Emanuele Magi

Subjects
Chromatography, biology, Extraction (chemistry), Proteolytic enzymes, Fraction (chemistry), Proteinase K, Analytical Chemistry, Bioavailability, Metal, Acetic acid, chemistry.chemical_compound, chemistry, Enzymatic hydrolysis, Environmental chemistry, visual_art, biology.protein, visual_art.visual_art_medium, Spectroscopy
Abstract

In this work we compared metal bioavailable fractions in marine sediments operationally measured by sequential selective extractions (in particular the labile fraction released by acetic acid) and by a biomimetic approach using a commercially available proteolytic enzyme, proteinase K, chosen because of its non-specific behaviour and because it is representative of the enzymes encountered in many deposit-feeding organisms. Different experimental conditions for enzymatic extraction were investigated and the enzyme was employed both untreated and thermally denatured to study metal release mechanisms (i.e. enzymatic hydrolysis and/or complexation). Extractable protein content was also measured to verify possible correlations with some metals. Considering the two sediments used in this work, the available fraction evaluated with a biomimetic approach was often significantly lower than the fraction released by the first step of selective extractions, as expected. Moreover a good correlation was found between the fraction of metal available to the enzyme and enrichment factors in the gut fluids of deposit-feeding organisms, suggesting that enzymatic approach is qualitatively more reliable than chemical extraction in replicating the mechanism of metal mobilization that occurs in the guts of deposit-feeders.

Published
2010

3. Using proteolytic enzymes to assess metal bioaccessibility in marine sediments

Author

Bignasca, Antonello, Ianni, Carmela, Magi, Emanuele, and Rivaro, Paola

Subjects
*PROTEOLYTIC enzymes, *METALS, *MARINE sediments, *ENZYMES, *ACETIC acid, *PROTEINASES, *BIOAVAILABILITY
Abstract

Abstract: In this work we tested two proteolytic enzymes (trypsin and pepsin) to evaluate metal bioaccessibility in marine sediments. Some working conditions were studied, in particular incubation time, enzyme concentration and solution/solid ratio, and metals release mechanisms were investigated using both untreated and denatured enzymes. The results obtained with trypsin and pepsin were compared with each other and with results from proteinase K extraction, carried out on the same sediment samples, following a procedure reported in the literature. Moreover, a comparison with the first step of BCR sequential procedure was made. Metal orders of mobility determined with the different enzymes and with acetic acid were compared with the one defined by the enrichment factors in the gut fluids of deposit-feeder organisms. The overall picture suggests that proteinase K has a better capability of reproducing natural phenomena and is therefore more suitable to determine metal bioaccessibility in marine sediments, when the target of the investigation is deposit-feeder organisms. [Copyright &y& Elsevier]

Published
2011
Full Text
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4. Metal bioavailability in marine sediments measured by chemical extraction and enzymatic mobilization

Author

Ianni, Carmela, Bignasca, Antonello, Magi, Emanuele, and Rivaro, Paola

Subjects
*BIOAVAILABILITY, *MARINE sediments, *HYDROLYSIS, *CHEMICAL speciation, *EXTRACTION (Chemistry), *PROTEOLYTIC enzymes
Abstract

Abstract: In this work we compared metal bioavailable fractions in marine sediments operationally measured by sequential selective extractions (in particular the labile fraction released by acetic acid) and by a biomimetic approach using a commercially available proteolytic enzyme, proteinase K, chosen because of its non-specific behaviour and because it is representative of the enzymes encountered in many deposit-feeding organisms. Different experimental conditions for enzymatic extraction were investigated and the enzyme was employed both untreated and thermally denatured to study metal release mechanisms (i.e. enzymatic hydrolysis and/or complexation). Extractable protein content was also measured to verify possible correlations with some metals. Considering the two sediments used in this work, the available fraction evaluated with a biomimetic approach was often significantly lower than the fraction released by the first step of selective extractions, as expected. Moreover a good correlation was found between the fraction of metal available to the enzyme and enrichment factors in the gut fluids of deposit-feeding organisms, suggesting that enzymatic approach is qualitatively more reliable than chemical extraction in replicating the mechanism of metal mobilization that occurs in the guts of deposit-feeders. [Copyright &y& Elsevier]

Published
2010
Full Text
View/download PDF

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