Purification and Characterization of DSIP‐Like Material From Ovine Pineal Glands: Possible Peptide‐Protein Interaction

摘要

The nonapeptide delta‐sleep‐inducing peptide (DSIP) has been isolated from venous blood of rabbits induced to sleep. Numerous reports have described sleep as well as extra‐sleep effects. Radiochemical and immunochemical data suggest a relationship of DSIP with the pineal gland supported by interactions of this peptide with pineal functions such as the serotonin N‐acetyltransferase activity. In order to demonstrate the natural occurrence of DSIP‐like material associated with high Mrproteins in the ovine pineal, organs were water‐extracted and fractionated by ultrafiltration and gel filtration. Radioimmunoassay (RIA) for DSIP‐like fragments of the fractions revealed considerable amounts of pineal DSIP‐like immunoreactivity (DSIP‐LI) apparently existing in small as well as large molecular forms. Acidification of large DSIP‐LI forms resulted in the elution from Sephadex G‐50 of Mr≤ 1,000 DSIP‐like material. This free DSIP‐LI form co‐eluted with the synthetic DSIP nonapeptide from μBondapak C18on high‐performance liquid chromatography. The results, therefore, appear to indicate the presence of a (biospecific) noncovalent intermolecular interaction of DSIP (1–9) with proteins (Mr