The peak height ratio of S-sulfonated transthyretin and other oxidized isoforms as a marker for molybdenum cofactor deficiency, measured by electrospray ionization mass spectrometry

Abstract

Molybdenum cofactor deficiency is a fatal neurological disorder, which follows an autosomal-recessive trait and is characterized by combined deficiency of the enzyme, sulfite oxidase, xanthine dehydrogenase and aldehyde oxidase. Early detection of molybdenum cofactor-deficient patients is essential for their proper care and genetic counseling of families at risk. We demonstrate the use of S-sulfonated transthyretin (TTR) as a marker for molybdenum cofactor deficiency. Plasma or sera obtained from 4 patients with molybdenum cofactor deficiency and 57 controls were studied by electrospray ionization mass spectrometry (ESIMS) following selective enrichment of TTR by immunoprecipitation using protein G/A agarose. The data obtained from molybdenum cofactor deficiency samples indicated a strong increase in the peak height of S-sulfonated TTR. A more significant difference was revealed if the peak height ratio of S-sulfonated TTR and the sum of the other oxidized TTR were determined. By accurate determination of the ratio, the samples of molybdenum cofactor deficiency patients could clearly be distinguished from controls without molybdenum cofactor deficiency.

Direct targeting of human plasma for matrix‐assisted laser desorption/ionization and analysis of plasma proteins by time of flight‐mass spectrometry

“…Major spots in Fig. 1 were identified [7,23], but the low-molecular-mass proteins are not well resolved compared to the mass spectrometric results of the corresponding proteins [15][16][17][19][20][21]. The reported MALDI- MS spectra showed that the plasma lipoproteins have been dissociated into their component apolipoproteins, possibly because of the sample treatment with a matrix solution which contains TFA and ACN [19].…”

“…In this study, seven isoform of TTR are detected by MALDI-TOF-MS. The prominent peak 29 was assigned to be the unmodified TTR and peak 30 was an isoform sulfonated at Cys10 [14,15]. Peaks 31, 32, and 35 were assigned to be TTR-cysteinylated, TTR conjugated with cysteinylglycine, and TTR conjugated with glutathione, all at Cys10 residue [35].…”

“…MALDI-TOF-MS on microorganisms (mostly bacteria) to fingerprint proteins has been developed for fast characterization of a single colony [12,13]. MS of intact proteins has been used for diagnosis purposes, polymorphism profiling or characterization of new isoforms, in which plasma is the most common source to prepare the target proteins [14][15][16][17][18][19][20][21]. However, as far as we know, MS on whole plasma has not been reported.…”

“…However, as far as we know, MS on whole plasma has not been reported. Actually, all the plasma protein studies by MS included complex separation/purification procedures prior to MS analysis, e.g., transthyretin (TTR) was normally purified by immunoprecipitation followed by LC [15][16][17], while apolipoproteins were purified using immunoaffinity chromatography or fractionated by centrifugation [19][20][21]. Electrophoresis 2005Electrophoresis , 26, 2823Electrophoresis -2834 In this paper, we describe a method for direct MALDI-TOF-MS analysis of human plasma proteins without using any prior purification or separation procedures.…”

Detection of Genetic Variants of Transthyretin by Liquid Chromatography–Dual Electrospray Ionization Fourier-Transform Ion-Cyclotron-Resonance Mass Spectrometry

“…Wada et al (12 ) were the first to perform the analysis of tryptic fragments of TTR by MS. This spawned several other mass spectrometric approaches to analyze and catalog TTR for any variations that differ from the wild-type amino acid sequence (6,(13)(14)(15)(16)(17)(18)(19)(20).…”