title: Cerebroside sulfate activator protein (Saposin B): chromatographic and electrospray mass spectrometric properties.
abstract: Cerebroside sulfate activator protein is a small, heat-stable protein that is exceptionally resistant to proteolytic attack. This protein is essential for the catabolism of cerebroside sulfate and several other glycosphingolipids. Protein purified from pig kidney and human urine was extensively characterized by reversed-phase liquid chromatography and electrospray mass spectrometry. These two sources revealed 20 and 18 different molecular isoforms of the protein, respectively. Plausible explanations of the structures of the majority of these isoforms can be made on the basis of accurate molecular mass assignments. The reversed-phase chromatographic and electrospray mass spectrometric properties of enzymatically deglycosylated and disulfide-reduced protein were also compared. In addition to a demonstration of the power of electrospray ionization mass spectrometry for revealing a wealth of information on protein microheterogeneity and structural detail, the results also demonstrate the utility of this technique for monitoring spontaneous chemical and enzymatically mediated changes that occur as a result of metabolic processing and protein purification.
authors.affiliation: Pasarow Mass Spectrometry Laboratory, Department of Psychiatry and Biobehavioral Sciences and the Neuropsychiatric Institute and Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, USA. faull@chem.ucla.edu
authors.forename: K F
authors.initials: KF
authors.lastname: Faull
authors.forename: J P
authors.initials: JP
authors.lastname: Whitelegge
authors.forename: J
authors.initials: J
authors.lastname: Higginson
authors.forename: T
authors.initials: T
authors.lastname: To
authors.forename: J
authors.initials: J
authors.lastname: Johnson
authors.forename: A N
authors.initials: AN
authors.lastname: Krutchinsky
authors.forename: K G
authors.initials: KG
authors.lastname: Standing
authors.forename: A J
authors.initials: AJ
authors.lastname: Waring
authors.forename: R L
authors.initials: RL
authors.lastname: Stevens
authors.forename: C B
authors.initials: CB
authors.lastname: Fluharty
authors.forename: A L
authors.initials: AL
authors.lastname: Fluharty
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004578:Electron Spin Resonance Spectroscopy; D020536:Enzyme Activators / Q000737:chemistry* / Q000302:isolation & purification / Q000652:urine; D005947:Glucose / Q000737:chemistry; D006023:Glycoproteins / Q000737:chemistry* / Q000302:isolation & purification / Q000652:urine; D006801:Humans; D007668:Kidney / Q000737:chemistry; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D049231:Saposins; D049128:Sphingolipid Activator Proteins; D013552:Swine
chemical_list: D020536:Enzyme Activators; D006023:Glycoproteins; C483345:PSAP protein, human; D049231:Saposins; D049128:Sphingolipid Activator Proteins; D005947:Glucose