title: Characterization of the carrier protein of digoxin-like immunoreactive substance in plasma.
abstract: The presence of an endogenous digoxin-like immunoreactive substance(s) (DLIS) has been reported in the plasma and urine of experimental animals and humans. This substance might have a role in arterial hypertension. Although the chemical structure of DLIS is at present unknown, several studies indicate that DLIS has a low molecular weight and is reversibly bound in serum to carrier proteins. We have investigated the carrier protein of DLIS in chromatographic studies, using neonate plasma eluted on a Sephadex G200 column. The chromatographic profile of digoxin-like immunoreactivity showed a major peak with a molecular weight of approximately 60,000 daltons and a smaller peak eluted after the salt region. When the major peak was chromatographed on a Sephadex G100 column only one single peak was obtained, which closely coincided with the elution peak of albumin. Chromatographic separation of neonate plasma on a Sephadex G25 revealed a major post-salt immunoreactive peak. When these fractions were incubated with purified human albumin and separated again on the Sephadex G25, a large immunoreactive peak corresponding to albumin was again found while the immunoreactivity after salt completely disappeared. Our data therefore strongly suggest that the endogenous digitalis-like factor is carried in plasma by albumin.
mesh_terms: D001798:Blood Proteins / Q000378:metabolism*; D002298:Cardenolides; D002352:Carrier Proteins / Q000097:blood*; D002852:Chromatography, Ion Exchange; D004077:Digoxin; D006801:Humans; D007231:Infant, Newborn; D008970:Molecular Weight; D011485:Protein Binding; D012503:Saponins; D012709:Serum Albumin / Q000378:metabolism*
chemical_list: D001798:Blood Proteins; D002298:Cardenolides; D002352:Carrier Proteins; D012503:Saponins; D012709:Serum Albumin; C034504:digoxin-like factors; D004077:Digoxin