Fluorescence studies on the interaction of β2-microglobulin and metallothionein

  • Noel S. Quiming Department of Physical Sciences & Mathematics, University of the Philippines Manila, Manila
  • James A. Villanueva Institute of Chemistry, University of the Philippines, Quezon City
  • Marilou G. Nicolas Department of Physical Sciences & Mathematics, University of the Philippines Manila, Manila
Keywords: metallothionein, β2-microglobulin, amyloidosis, fluorescence spectroscopy

Abstract

β2-microglobulin (2m) is a small, major histocompatibility complex classI-associated protein that undergoes aggregation and accumulates as amyloid deposits in human tissues as a consequence of long-term hemodialysis. The exact mechanism of its aggregation to form insoluble fibrils is unknown. Determining the factors which may lead to β2m fibril formation will be of great help in elucidating the mechanism of β2m aggregation. This study was undertaken to determine the interaction of β2m with the stress protein metallothionein (MT) using fluorescence spectroscopy. All spectroscopic probes gave proofs on the interaction of β2m and MT. Fluorescence quenching of the tryptophan residues of β2m with and without MT were measured at different pH values. At pH 4.0, 7.0, and 8.0 quenching of β2m fluorescence in the presence of MT were observed suggesting the possibility of binding of the two proteins. Fluorescence quenching experiments were also performed using acrylamide and KI as quenchers. Quenching of β2m in the presence of MT gave nonlinear Stem-Volmer plots showing a dynamic quenching mechanism. In addition, the larger quenching constants when MT was present indicated that the interaction of the two proteins resulted in the exposure of the tryptophan residues of β2m. To date, this is the first report on the interaction of the two proteins. The interaction between β2m and MT may give insights in further understanding the mechanism of β2m fibril formation.
Published
2003-06-01
How to Cite
Quiming, N. S., Villanueva, J. A., & Nicolas, M. G. (2003). Fluorescence studies on the interaction of β2-microglobulin and metallothionein. KIMIKA, 19(1), 1-6. https://doi.org/10.26534/kimika.v19i1.1-6
Section
Research Articles