Article

European Biophysics Journal

, 35:439

First online:

Micro-heterogeneity and aggregation in β2-microglobulin solutions: effects of temperature, pH, and conformational variant addition

  • Roberto PiazzaAffiliated withDipartimento di Ingegneria Nucleare, Politecnico di Milano Email author 
  • , Matteo PiernoAffiliated withDipartimento di Ingegneria Nucleare, Politecnico di Milano
  • , Sara IacopiniAffiliated withDipartimento di Ingegneria Nucleare, Politecnico di Milano
  • , Palma MangioneAffiliated withLaboratorio di Biotecnologia IRCCS Policlinico San Matteo e Dipartimento di Biochimica, Universitá di Pavia
  • , Gennaro EspositoAffiliated withDipartimento di Scienze e Tecnologie Biomediche, Universitá di Udine
  • , Vittorio BellottiAffiliated withLaboratorio di Biotecnologia IRCCS Policlinico San Matteo e Dipartimento di Biochimica, Universitá di Pavia

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Abstract

We show that β2-microglobulin solutions in physiological conditions contain a tiny fraction of aggregates, which can hardly be filtered out and tend to re-form spontaneously. At physiological pH the fractional amount and size distribution of the latter aggregates do not depend on temperature. Conversely, in the pH range typical of the peri-articular tissue acidosis that often occurs in hemodialysis, temperature increase leads to fast and irreversible growth of the aggregates. Quite similar, but strongly enhanced aggregation effects can be induced even in physiological conditions by adding a very small amount of ΔN6, a naturally occurring truncated isoform of β2-m known to promote fibrillogenesis.