Human submandibular gland tissue in culture 2. Nickel affinity to secretory proteins

In view of the exposure to nickel through the oral cavity the relation between this metal (as 63NiCl2) and salivary macromolecules was studied by tissue culture, isoelectric focusing and equilibrium dialysis. During cultivation of human submandibular gland tissue, small amounts of nickel were incorporated into macromolecules with an isoelectric point of about 4.4 and approximately 7.5. No affinity independent of the protein synthesis was revealed between nickel and submandibular proteins, including the acidic, viscous, sulphate-incorporating glycoproteins. It is therefore possible that a nickel-containing metalloprotein is present in the submandibular secretion, but a complex formation between nickel and macromolecules similar to the nickel-albumin transport system in plasma was not found. The affinity of nickel to small molecular substances in the secretion was not studied.