title: MALDI-TOF mass spectrometry of naturally occurring mixtures of monorhamnolipids and dirhamnolipids.
abstract: MALDI-TOFMS approaches have been developed for high-throughput screening of naturally occurring mixtures of rhamnolipids from Pseudomonas spp. Monorhamnolipids and dirhamnolipids are readily distinguished by characteristic molecular adduct ions, [M+Na](+) and [M-H+Na(2)](+), with variously acylated rhamnolipids differing by 28 mu. Following proton-deuterium exchange, deuterated [M+Na-4(1)H+4(2)H](+) and [M+Na-6(1)H+6(2)H](+) ions are observed for the monorhamnolipids and dirhamnolipids, respectively, which allows rapid identification of these molecules. The described approach has been validated by compositional analysis using GC/MS, fractionation by RPHPLC, and analysis by 1D and 2D NMR spectroscopy. MALDI-TOFMS analysis allows the rapid screening of variously acylated rhamnolipids, and has potential for selective identification of new surfactants from microbial strains.
authors.affiliation: Bioproducts and Biocatalysis, USDA-ARS-NCAUR, 1815 North University Street, Peoria, IL 61604, USA. neil.price@ars.usda.gov
authors.forename: Neil P J
authors.initials: NP
authors.lastname: Price
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Ray
authors.forename: Karl
authors.initials: K
authors.lastname: Vermillion
authors.forename: Tsung-Min
authors.initials: TM
authors.lastname: Kuo
mesh_terms: D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006017:Glycolipids / Q000737:chemistry* / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D006017:Glycolipids; C418382:rhamnolipid