Sulfation of gastrin in Zollinger--Ellison sera: evidence for association between sulfation and proteolytic processing.

Sulfated gastrins were quantitated in sera from 15 patients with the Zollinger--Ellison syndrome (ZES) by specific radioimmunoassays. The total concentration of gastrin varied from 174 to 285 000 pmol/l. Sulfated gastrins constituted 44.8 +/- 5.5% (mean +/- S.E.M.) of the gastrins in ZES sera compared with 37.7 +/- 1.9% in sera from 100 control subjects (P greater than 0.1). There was no correlation between gastrin concentration and sulfation (r = 0.40). Gel and ion-exchange chromatography showed that up to 90% of the gastrins could be in the sulfated form. The highest degree of sulfation was found in sera where the small gastrin components dominated. Thus, the percentage of small gastrins (G-17 and G-14) correlated with the degree of sulfation (N = 15, r = 0.75, P less than 0.01). We suggest therefore that proteolytic processing of the gastrin precursor and sulfation of tyrosyl are associated.