Evaluation of arsenic species–protein binding in cardiovascular tissues by bidimensional chromatography with ICP-MS detection

Abstract

Intracellular As–protein binding in cytosol extracts of auricle and saphenous tissues of As impacted people was evaluated by bidimensional chromatography (size exclusion and FPLC-UV-ICP-MS). The fractionation of cytosol using Superdex (0.1–7 kDa), Phenomenex (1–300 kDa) and MonoQ HR 5/5 columns shows that As is distributed in a wide range of contiguous fractions for each column, the percentages of As in the fractions collected being 8, 25 and 50%, respectively. The FPLC-UV-ICP-MS chromatograms of the fractions from the above columns show that As is bound to biocompounds of different molecular mass through vicinal sulfur groups. The monitoring of S, Cu and P present in the fractions show that As and Cu are usually bound to the same type of proteins, some of which contain P. No significant differences were observed between the auricle and saphenous tissues in the As fractionation behaviour of the cytosol. From the Superdex column it can be deduced that the molecular weight of the peptides associated to As are within the range 330–4600 Da, which could correspond to metallothioneins, glutathione (As(SG)₃) and cysteine (As(Cys)₃) complexes. The As–proteins of molecular weight within the range 0.3–12.4 kDa from the Phenomenex fractioning could correspond to transferrine and hemoglobin. This work can be considered as a first step in the investigation of As bioaccumulation and the biochemical response of cardiovascular tissues proceeding from individuals chronically impacted by inorganic As when the source for human As uptake is drinking water.