Adsorption of human serum albumin on the chrysotile surface: a molecular dynamics and spectroscopic investigation

Our plain-English summary of Adsorption of human serum albumin on the chrysotile surface: a molecular dynamics and spectroscopic investigation, by R. Artali, A. Del Pra, E. Foresti, et al (Journal of the Royal Society, Interface, 2008).

The study

• Authors: R. Artali, A. Del Pra, E. Foresti, I.G. Lesci, N. Roveri, P. Sabatino
• Journal: Journal of the Royal Society, Interface
• Published: 2008;5(20):273-83
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The human serum albumin (HSA) secondary structure modifications induced by the chrysotile surface have been investigated via computational molecular dynamics (MD) and experimental infrared spectroscopy (FTIR) on synthetic chrysotile nanocrystals coated with different amount of HSA. MD simulations, conducted by placing various albumin subdomains close to the fixed chrysotile surface, show an initial adsorption phase, accompanied by local rearrangements of the albumin motifs in contact with the chrysotile layer. Next, large-scale rearrangements follow with consequent secondary structure modifications. Gaussian curve fitting of the FTIR spectra obtained for HSA-coated synthetic chrysotile nanocrystals has allowed the quantification of HSA structural modifications as a function of the amount of protein adsorbed. The experimental results support the atomistic computer simulations providing a realistic description of the adsorption of plasma proteins onto chrysotile and unravelling a key step in the understanding of asbestos toxicity.

In plain English

This was a laboratory and computer-simulation study, not a study of people or animals. The authors examined how human serum albumin (HSA), a blood protein, changes shape when it sticks to chrysotile. In computer simulations, they placed four selected pieces (subdomains) of the HSA molecule next to a flat, fixed chrysotile surface, because the whole protein was too large to simulate. In the laboratory, they coated synthetic chrysotile nanocrystals, made to have a uniform composition, with different amounts of HSA. They then measured the protein's structure by infrared spectroscopy on freeze-dried samples. In the simulations, the protein pieces first lost part of their coiled (alpha-helix) structure near the surface. They then spread out until their helices were fully unfolded, with contact area rising by factors of about 2.75 to 3.15. In the experiments, alpha-helix content was 33% in HSA not on chrysotile and 14% to 15% in HSA on chrysotile. The authors concluded that the experiments supported the simulations and gave insight into asbestos toxicity. They noted that the flat surface was an idealized approximation of real asbestos.

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 study combining computer simulations (molecular mechanics and molecular dynamics) with infrared spectroscopy (FTIR) experiments; no human or animal subjects
• Who was studied: Four selected subdomains (zones 1 to 4) of the human serum albumin molecule simulated on a flat chrysotile surface, plus synthetic chrysotile nanocrystals coated with different amounts of HSA in the laboratory (Universities of Milano and Bologna, Italy)
• Exposure: Synthetic stoichiometric chrysotile nanocrystals (made in the laboratory, not mined chrysotile) exposed to HSA solutions in phosphate buffer at pH 7.4 at different protein concentrations. The methods state 0.3 to 2.5 mg per ml; the results describe 0.5, 1.0 and 4 mg per ml.
• Main results:
  • In the simulations' initial adsorption step, all four albumin subdomains adsorbed onto the chrysotile surface with partial loss of their secondary structure near the surface
  • In the later molecular dynamics stage, the subdomains spread on the surface: all alpha-helices were fully unfolded and nearly all amino acids touched the chrysotile plane, forming a single layer
  • After full spreading in the simulations, the contact area of the four zones increased by factors of approximately 2.75, 2.98, 2.83 and 3.15, respectively
  • In the FTIR experiments at low coverage, HSA on chrysotile showed a drastically reduced alpha-helix content, with increased beta-sheet and random coil content, compared with HSA not on chrysotile
  • In the secondary-structure table, freeze-dried HSA not on chrysotile had 33% alpha-helix (plus or minus 1). HSA on chrysotile had 14%, 15% and 14% alpha-helix at surface coverages of 1.04, 1.55 and 2.04 mg per square metre. The plus-or-minus values are standard deviations from five spectra.
  • As surface coverage increased, beta-sheet content decreased and beta-turn content increased, while alpha-helix content stayed about the same
  • The greatest differences in protein shape appeared between low and medium surface coverage
• The authors' conclusion: The authors concluded that their experimental results supported the computer simulations as a realistic description of how plasma proteins adsorb onto chrysotile, gaining insight into the mechanism of asbestos toxicity
• Limitations the authors state:
  • The flat chrysotile surface used in the simulations was an idealized, simplified stand-in for a real asbestos surface
  • Real serpentine asbestos is more complex, made of tiny randomly oriented microcrystals whose edges and grooves may change protein adsorption
  • Only selected pieces of the albumin molecule were simulated, because the whole molecule was too large

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Infrared Spectroscopy (IR).

Related studies

• Synthetic chrysotile nanocrystals as a reference standard to investigate surface-induced serum albumin structural modifications — P. Sabatino, L. Casella, et al. (2007)
• Adsorption of bovine serum albumin onto synthetic Fe-doped geomimetic chrysotile — A. Adamiano, I.G. Lesci, et al. (2015)
• Interaction of bovine serum albumin with chrysotile: spectroscopic and morphological studies — G. Falini, E. Foresti, et al. (2006)
• Infrared and nuclear magnetic resonance studies of some surface properties of asbestos-albumin interactions — R. Dumitru-Stănescu, C. Mandravel, et al. (1994)
• Serum albumin as a significant prognostic factor in patients with malignant pleural mesothelioma — Z.H. Yao, G.Y. Tian, et al. (2014)
• Adsorption isotherms of albumin and ferritin on Rhodesian chrysotile: effects of magnesium depletion — F. Valerio, M. Veggi, et al. (1980)

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