Characterisation of cobalt‐binding proteins in occupational cobalt exposuret†

In animal experimentations cobalt is found to be carcinogenic under conditions which are comparable with a possible exposure of human beings at the workplace.1,2 Little is known about binding and distribution of incorporated cobalt in blood. Blood, serum and plasma of workers occupationally exposed to cobalt were analyzed concerning cobalt‐binding. The samples were focused by preparative IEF in layers of granulated gels. The cobalt concentrations in the isolated fractions were measured with the aid of flameless atomic absorption spectrometry. The whole blood samples exhibit peaks with different sizes in the pH‐5‐ and ‐7‐range. The proportion of these peaks can change with individual samples. In serum and plasma cobalt is found only in the pH‐5‐range. When separated by gelelectrophoresis under denaturating conditions the cobalt‐fractions in all blood, serum and plasma samples shows a similar protein pattern. Several proteins with different molecular weights are detected in the pH‐5‐fractions, whereas only hemoglobin is found in the pH‐7‐fractions. In agreement with these results is the refocusing in ultrathin‐layer of polyacrylamide. Heterogeneous protein patterns are demonstrated with the pH‐5‐fractions; the pH‐7‐fractions yield only the hemoglobin pattern. In vivo cobalt is bound to plasma proteins‐perhaps‐albumin3,4‐and hemoglobin. Till now the chemical structure of the binding is unknown.