title: In situ analysis of plant tissue underivatized carbohydrates and on-probe enzymatic degraded starch by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry by using carbon nanotubes as matrix.
abstract: Underivatized carbohydrates of tulip bulb and leaf tissues were characterized in situ by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) by using carbon nanotubes (CNTs) as matrix. Two sample preparation methods--(i) depositing CNTs on the fresh tissue slices placed on the probe and (ii) locating semitransparent tissues on a dried layer of CNTs on the probe--were examined. Furthermore, practicability of in situ starch analysis by MALDI-TOF MS was examined by detection of glucose originated from on-probe amyloglucosidase-catalyzed degradation of starch on the tissue surface. Besides, CNTs could efficiently desorb/ionize natural mono-, di-, and oligosaccharides extracted from tulip bulb tissues as well as glucose resulting from starch enzymatic degradation in vitro. These results were compared with those obtained by in situ MALDI-TOF MS analysis of similar tissues. Positive ion mode showed superior signal reproducibility. CNTs deposited under semitransparent tissue could also desorb/ionize neutral carbohydrates, leading to nearly complete elimination of matrix cluster signals but with an increase in tissue-originated signals. Furthermore, several experiments were carried out to compare the efficiency of 2,5-dihydroxybenzoic acid, nor-harmane, alpha-cyano-4-hydroxycinnamic acid, and CNTs as matrices for MALDI of neutral carbohydrates from the intact plant tissue surface and for enzymatic tissue starch degradation; these results are discussed in brief. Among matrices studied, the lowest laser power was needed to acquire carbohydrate signals with high signal-to-noise ratio and resolution when CNTs were used.
authors.affiliation: United Graduate School of Agricultural Sciences, Ehime University, Matsuyama 790-8566, Japan.
authors.forename: Yousef
authors.initials: Y
authors.lastname: Gholipour
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nonami
authors.forename: Rosa
authors.initials: R
authors.lastname: Erra-Balsells
mesh_terms: D053000:Analytic Sample Preparation Methods; D002241:Carbohydrates / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D005087:Glucan 1,4-alpha-Glucosidase / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D037742:Nanotubes, Carbon; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013213:Starch / Q000378:metabolism*; D031447:Tulipa / Q000737:chemistry* / Q000166:cytology* / Q000201:enzymology
chemical_list: D002241:Carbohydrates; D037742:Nanotubes, Carbon; D013213:Starch; D005087:Glucan 1,4-alpha-Glucosidase; D005947:Glucose