Comparison of Nonmetal and Metal Hydrophilic Photosensitizer, ATX‐S10 (Na) and ATN‐2, Binding with Human Serum Proteins Using Spectrophotometry^¶

Abstract

Intermolecular interactions of human serum proteins with a hydrophilic nonmetalloporphyrin, 13,17‐bis(1‐carboxy‐propionyl)carbomoylethyl‐8‐ethenyl‐2‐hydroxy‐3‐hydroxy‐iminoethylidene‐2,7,12,18‐tetramethylporphyrin sodium salt (ATX‐S10 (Na)), or a hydrophilic gallium‐metalloporphyrin, diethylenetriamine pentaacetic acid ester of 2‐[1‐(2‐hydroxyethoxy)ethyl]‐4‐vinyl‐deuteroporphyrin (IX) Ga complex (ATN‐2), were investigated using spectrophotometry. ATX‐S10 (Na) caused a bathochromic shift with albumin, high‐density lipoprotein and low‐density lipoprotein, but little or no shift was observed with hemopexin, transferrin and immuno‐globulin G. In contrast, ATN‐2 displayed a bathochromic shift only with hemopexin. These results suggest that the association energy of ATX‐S10 (Na) with albumin might be slightly greater than that with lipoproteins and that of ATN‐2 with hemopexin might be greater than that with other serum proteins.