Mass Spectral Characterization of an Endogenous Digitalislike Factor From Human Plasma

• Published in: Hypertension (Dallas, Tex. 1979) Vol. 17; no. 6, Part 2; pp. 930 - 935
• Main Authors: Mathews, W Rodney, DuCharme, Donald W, Hamlyn, John M, Harris, Douglas W, Mandel, Frederic, Clark, Michael A, Ludens, James H
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Philadelphia, PA American Heart Association, Inc 01-06-1991; Hagerstown, MD Lippincott
• Subjects: Acetylation; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Blood Proteins - chemistry; Blood Proteins - isolation & purification; Blood Proteins - metabolism; Carbohydrates; Cardenolides; Chromatography, High Pressure Liquid; Digoxin; Fundamental and applied biological sciences. Psychology; Heterosides; Humans; Mass Spectrometry; Other biological molecules; Ouabain - metabolism; Saponins; Sodium-Potassium-Exchanging ATPase - antagonists & inhibitors; Spectrometry, Mass, Fast Atom Bombardment
• ISSN: 0194-911X; 1524-4563
• DOI: 10.1161/01.hyp.17.6.930

A sodium pump inhibitor has been isolated from human plasma and extensively purified. This material, endogenous digitalislike factor, was examined by a variety of mass spectrometric techniques. A low-resolution fast atom bombardment mass spectrometric analysis of a sample of purified endogenous digitalislike factor revealed a single unique molecular ion in the mass range 100-2,500. The accurate mass was determined to be 585.295 Da in a second highresolution fast atom bombardment mass spectrometric experiment Based on this accurate mass, the elemental composition of endogenous digitalislike factor was determined and found to be identical to the elemental composition of the known cardenolide ouabain. Direct comparison of ouabain and endogenous digitalislike factor by linked scan tandem mass spectrometry, derivatization with acetic anhydride coupled with fast atom bombardment mass spectrometry, and analytical high-performance liquid chromatography failed to reveal any differences. We conclude that the endogenous digitalislike factor isolated from human plasma is ouabain or a closely related isomer. (Hypertension 1991;17:930-935)