Adsorption of proteins by chrysotile and crocidolite: role of molecular weight and charge density

Our plain-English summary of Adsorption of proteins by chrysotile and crocidolite: role of molecular weight and charge density, by F. Valerio, D. Balducci, A. Lazzarotto (Environmental Research, 1987).

The study

• Authors: F. Valerio, D. Balducci, A. Lazzarotto
• Journal: Environmental Research
• Published: 1987;44(2):312-20
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Transferrin, gamma-globulin, fibrinogen, aldolase, albumin, and cytochrome c at concentration of 0.45 muMole/liter were treated with chrysotile and crocidolite fibers. Specific adsorption for each protein and correlations between protein molecular weight and charge density in experimental conditions were evaluated. Chrysotile showed the highest absorption capability, particularly toward albumin and cytochrome c. Affinity for fibers was poorly linked to protein molecular weight; on the contrary, a good correlation with protein charge density was found. The sign of charge on fibers and proteins seemed to play a minor role in adsorption.

In plain English

This was a laboratory experiment by researchers at a cancer research institute in Genova, Italy. It studied how strongly six proteins stick to (are adsorbed by) two types of asbestos fiber: Rhodesian chrysotile and crocidolite. The proteins were transferrin, gamma-globulin, fibrinogen, aldolase, albumin and cytochrome c. Each protein was mixed in solution with fibers for 2 hours at 37°C, and the authors asked whether protein size (molecular weight) or electric charge density explained how much protein stuck to the fibers. No people, cells or animals were studied. On chrysotile, albumin was adsorbed most (0.45 µM/g of fiber) and aldolase least (0.05 µM/g). Crocidolite adsorbed less overall than chrysotile: most for albumin (0.34 µM/g) and least for fibrinogen (0.02 µM/g). Adsorption was not directly related to molecular weight. It tended to rise with charge density. The authors concluded that fiber surface area and protein charge density seemed to play an important role, while molecular weight and the type of charge seemed of little importance. They noted that only a small number of proteins was tested.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: laboratory (in vitro) adsorption experiment measuring how much of each protein in solution was taken up by asbestos fibers
• Who was studied: No human or animal subjects. Six purified proteins were tested: human transferrin, human gamma-globulin, human fibrinogen, aldolase purified from rabbit muscle, human albumin, and cytochrome c. The work was done at the Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
• Exposure: UICC reference Rhodesian chrysotile and crocidolite fibers (20 mg, sonicated for 20 minutes) in buffer at pH 7.4. Each protein was added to a final concentration of 0.45 µM and left for 2 hours at 37°C.
• Main results:
  • On chrysotile, all proteins were adsorbed to varying degrees. Aldolase was adsorbed least (0.05 µM/g of fiber) and albumin most (0.45 µM/g of fiber).
  • Adsorption did not show a direct correlation with protein molecular weight.
  • On chrysotile, specific adsorption tended to increase as protein charge density increased.
  • On chrysotile, the proteins with a net positive charge (aldolase, cytochrome c) had significantly lower adsorption values.
  • Crocidolite adsorbed less protein overall than chrysotile.
  • On crocidolite, albumin was adsorbed most (0.34 µM/g).
  • On crocidolite, fibrinogen was adsorbed least (0.02 µM/g of fiber).
  • For both fiber types, adsorption of negatively charged proteins rose in a straight-line relationship with charge density. Fibrinogen on crocidolite was the exception. Positively charged proteins showed the same linear pattern, but their overall adsorption was significantly lower.
  • The ratio of chrysotile to crocidolite adsorption matched the ratio of the two fibers' surface areas for cytochrome c, transferrin, globulin and aldolase. Albumin and especially fibrinogen did not follow this pattern.
• The authors' conclusion: The authors concluded that molecular weight and the type of charge on fibers or proteins seem to be of little importance. In their view, fiber surface area and protein charge density (especially for chrysotile) seem to play an important role in adsorption.
• Limitations the authors state:
  • Only a small number of proteins was tested.
  • Sonication may have changed the fibers, so their actual surface areas under the test conditions probably differed from the published reference values.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile, Crocidolite.

Medical terms in this study, explained in our Lexicon: Chrysotile, Crocidolite.

Related studies

• Selective adsorption of serum proteins by chrysotile and crocidolite — F. Valerio, D. Balducci, et al. (1986)
• Two dimensional protein patterns of bronchoalveolar lavage fluid from non-smokers, smokers, and subjects exposed to asbestos — M. Lindahl, T. Ekström, et al. (1996)
• Adsorption of human serum albumin on the chrysotile surface: a molecular dynamics and spectroscopic investigation — R. Artali, A. Del Pra, et al. (2008)
• Vitronectin adsorption to chrysotile asbestos increases fiber phagocytosis and toxicity for mesothelial cells — J. Wu, W. Liu, et al. (2000)
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• Plasmid DNA is released from nanosized acicular material surface by low molecular weight oligonucleotides: exogenous plasmid acquisition mechanism for penetration intermediates based on the Yoshida effect — N. Yoshida, K. Ide (2008)

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