Sulfation of gastrin: effect on immunoreactivity.
The effect of sulfuric acid esterification of Tyr-12 in gastrin-17 on immunoreactivity was evaluated by the ability of seventeen antisera raised against non-sulfated gastrin-17 to bind sulfated gastrins in extracts of gastrinoma and antral tissue. Using non-sulfated Tyr-12 iodinated gastrin as tracer, and non-sulfated gastrin-17 as standard the antisera showed three different patterns of reactivity: Three antisera (Nos. 2602, 2605 and 4562) bound sulfated gastrins with low (4-23%) potency; four antisera (Nos. 2604, 2720, 4710 and 4713) measured sulfated gastrins with a potency similar to that of non-sulfated gastrins (81-100% crossreactivity); whereas ten antisera (Nos. 2601, 2606, 2609, 2716, 2717, 2718, 4556, 4559, 4560 and 4563) displayed enhanced reactivity with sulfated gastrins (130-373% crossreactivity). Using Gly-2 iodinated gastrin as tracer, the latter type of antisera reacted almost equally with sulfated and non-sulfated gastrins, suggesting that the apparent increase in binding of sulfated gastrins rather is due to increased displacement of Tyr-12 iodinated gastrin. The results show that derivatization of amino acid residues greatly influences antibody binding.
D000818:Animals; D000918:Antibody Specificity; D004951:Esterification; D005753:Gastric Mucosa / Q000032:analysis; D005755:Gastrins / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007120:Immunochemistry; D011817:Rabbits; D011863:Radioimmunoassay; D013464:Sulfuric Acids; D014443:Tyrosine; D015043:Zollinger-Ellison Syndrome / Q000032:analysis
D005755:Gastrins; D013464:Sulfuric Acids; D014443:Tyrosine