Studies on pituitary lactogenic hormone. XXI. Immunochemical studies of the sheep hormone

Abstract

Rabbit antisera to ovine prolactin and performic acid-oxidized prolactin have been prepared. Quantitative immunochemical studies with these antisera were carried out by both precipitin and complement fixation procedures. It was found that the extent of precipitin reaction of the unmodified hormone with the antiserum to the oxidized hormone was far greater than that of the oxidized antigen with the antiserum to the unmodified hormone. A total cross reaction between the periodate-treated hormone and antisera to the unmodified hormone was demonstrated by quantitative immunochemical techniques. Similar studies with an active core obtained from a chymotryptic digest of ovine prolactin indicated that the molecular integrity of the hormone protein is not essential for immunochemical activity. Anaphylactic shock experiments with guinea pigs showed that the antigenicity of ovine prolactin is reduced by partial hydrolysis with chymotrypsin.