A method for quantifying indole-3-acetic acid (IAA) and its conjugates with the six amino acids, Ala, -Asp, -Ile, -Glu, -Phe and -Val, in rice (Oryza sativa) by using high-performance liquid chromatography coupled with electrospray ionization and tandem mass spectrometry (HPLC-ESI-MS/MS) is described. Samples from the rice plant or callus were treated with 80% acetone in water containing 2.5 mM...

High-performance liquid chromatography-diode array detector (HPLC-DAD) coupled with electronspray mass spectrometry (ESI-MS) was used to detect the flavonoid profile in lemon juices obtained from the main Sicilian cultivars (Femminello comune, Monachello, and Interdonato). Significant amounts of an unusual constituent were found in the lemon juice of the above-mentioned cultivars together with ...

The application of continuous flow-extractive desorption electrospray ionization (CF-EDESI), an ambient ionization source demonstrated previously for use with intact protein analysis, is expanded here for the coupling of reversed phase protein separations to mass spectrometry. This configuration allows the introduction of charging additives to enhance detection without affecting the chromatogra...

Cationic peanut peroxidase (CP) was isolated from peanut (Arachis hypogaea) cell suspension culture medium. CP is a glycoprotein with three N-linked glycan sites at Asn60, Asn144, and Asn185. ESI-MS of the intact purified protein reveals the microheterogeneity of the glycans. Tryptic digestion of CP gave a near complete sequence coverage by ESI-MS. The glycopeptides from the tryptic digestion w...

The compositions of paradoxin and taipoxin (PDx and TPx, respectively) were investigated using size exclusion chromatography (SEC) and nano-electrospray ionization mass spectrometry (nano-ESI-MS). The elution profiles from size exclusion chromatography of the venoms from Oxyuranus microlepidotus and Oxyuranus scutellatus were similar. Fractions corresponding to the trimeric toxins were treated ...

BACKGROUND Matrix effects in HPLC-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS)1 can cause differences in the ionization of an internal standard (IS) compared with the analyte of interest. Unless sample cleanup or chromatographic conditions eliminate or minimize ion suppression or enhancement, variability in interpatient matrices may cause erroneous results. A stable isotope...

A thorough analysis of the protein interaction partners of the yeast GTPase Gsp1p was carried out by a multidimensional chromatography strategy of strong cation exchange fractionation of peptides followed by reverse phase LC-ESI-MSMS using a QSTAR instrument. This dataset was then analyzed using the latest developmental version of Protein Prospector. The Prospector search results were also comp...

BACKGROUND The measurement of renin activity is complicated by difficulties in the quantification of angiotensin 1 (Ang1), the product of the renin-catalyzed reaction. We report an HPLC-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) method for the quantification of Ang1 as a measure of plasma renin activity (PRA). METHODS After incubation (37 degrees C for 3 or 18 h), samples were pre...