[Protein binding of gold in serum of patients treated with different gold preparations]

Binding of gold to serum proteins of patients treated with Na-aurothiomalate (AM), gold keratinate (GK) and triethylphosphine gold (PG) was compared. In addition the pattern of distribution of gold in serum of healthy donors after in vitro incubation with these compounds and with tetrachlorogoldacid (GC) was studied. Serum specimens were fractionated by gel filtration (Sephadex G 200), gold was measured by atomic absorption spectroscopy, concentration of protein was calculated by extinction at 280 nm. After incubation with AM, PG and GC in vitro gold binds to serumproteins rapidly and completely (concentration of gold with AM and GC about 5 mg/l, with PG about 1 mg/1). The distribution among the protein fractions is different, however. With AM and GC 94% of gold is bound to albumin and only 6% to globulin. The corresponding figures with PG are 70% respectively 30%. With GK gold binds not completely to serum proteins in vitro. Even after 24 hours incubation about 7% are unbound. The affinity to globulin is high with GK (20%). On principle the pattern of distribution of gold is the same in vivo. The concentration of gold in the serum was almost the same as during the in vitro experiments. No unbound gold was found with GK. The affinity to globulin increases from AM to GK and especially to PG. The reason for these typical patterns are at least in part different metabolic pathways of the gold compounds. These findings may explain some differences of efficacy of certain goldcompounds.