title: Quantification of endogenous alpha- and gamma-endorphins in rat brain by liquid chromatography-tandem mass spectrometry.
abstract: Quantification of alpha- and gamma-endorphins in rat brain using liquid chromatography-electrospray ionization-tandem mass spectrometry is described. [D-Ala(2)]-gamma-endorphin is used as an internal standard. The precursor-to-product ion MRM transitions for alpha-endorphin, gamma-endorphin, and [D-Ala(2)]-gamma-endorphin were m/z 873.6-->429.6; 929.6-->542.3; 936.6-->542.3, respectively. The method was validated in terms of linearity, specificity, sensitivity, recovery, precision, and accuracy. The assay was linear over a concentration range of 0.1-200 ng/mL with the limit-of-detection of 0.03 ng/mL and limit-of-quantification of 0.1 ng/mL. The endogenous concentrations of alpha- and gamma-endorphins in rat brains were 13.8+/-0.57 (mean+/-SD; n=5) and 2.5+/-0.43 ng/g of wet tissue weight, respectively.
authors.affiliation: Department of Chemistry, The University of Memphis, Campus Box 526060, Memphis, TN 38152, USA.
authors.forename: Hari
authors.initials: H
authors.lastname: Kosanam
authors.forename: Suma
authors.initials: S
authors.lastname: Ramagiri
authors.forename: Chhabil
authors.initials: C
authors.lastname: Dass
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D008297:Male; D008969:Molecular Sequence Data; D051381:Rats; D017208:Rats, Wistar; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D018822:alpha-Endorphin / Q000032:analysis* / Q000737:chemistry; D018823:gamma-Endorphin / Q000032:analysis* / Q000737:chemistry
chemical_list: D018822:alpha-Endorphin; D018823:gamma-Endorphin