Investigation of thermostable metalloproteins in Perna perna mussels from differentially contaminated areas in Southeastern Brazil by bioanalytical techniques

• Metals and thermostable metalloproteins in Perna perna mussels were investigated.
• Mussels from three metal-contaminated sites were compared to a reference site.
• Metalloproteins binding to non-essential metals indicate detoxification attempts.
• Toxic element accumulation and essential element dyshomeostasis were also observed.
• Unfortunately, the reference site also seems to be contaminated by toxic metals.

Metallomic studies regarding environmental contamination by metals are of value in elucidating metal uptake, trafficking, accumulation and metabolism in biological systems. Many proven bioindicator species, such as bivalves, have not yet, however, been well-characterized regarding their metalloprotein expression in response to environmental contaminants. In this context, the aim of the present study was to investigate metalloprotein expressions in the thermostable protein fraction of muscle tissue and digestive glands from mussels (Perna perna) from three differentially metal-contaminated sites in Southeastern Brazil in comparison with a reference site. The thermostable protein fractions were analyzed by SDS-PAGE and SEC-HPLC-ICP-MS. Metal content was also determined in both the crude and the purified extracts. Several inter-organ differences were observed, which is to be expected, while inter-site differences regarding thermostable protein content were also verified, indicating accumulation of these elements in muscle tissue and digestive glands and disruption of homeostasis of essential elements, with detoxification attempts by metal-bound proteins, since all metalloproteins present in both matrices eluted bound to at least one non-essential metal. These results are also noteworthy with regard to the adopted reference site, that also seems to be contaminated by toxic metals.