Detection by mass spectrometry of highly increased amount of S-sulfonated transthyretin in serum from a patient with molybdenum cofactor deficiency.
Serum transthyretin has several isoforms, most of which are caused by disulfide linkage with cysteine residue at position 10. We found an ion peak 80 D larger than unmodified transthyretin by electrospray ionization mass spectrometry and assigned it to S-sulfonated transthyretin. The peak height was <2% of total transthyretin in control sera from more than 200 individuals including infants. Transthyretin from a patient with molybdenum cofactor deficiency was analyzed, and the peak was prominent, higher than 85% of total transthyretin. In patients with this disease, the presence of elevated levels of sulfite leads to the formation of S-sulfonated cysteine. The peak can be used as a diagnostic marker for molybdenum cofactor deficiency, although more sera from patients with this disease should be tested.
Kishikawa
M
M
Department of Clinical Pathology, Osaka Medical College, Takatsuki, Japan.
Nakanishi
T
T
Shimizu
A
A
Yoshino
M
M
D002675:Child, Preschool; D003067:Coenzymes; D006801:Humans; D007223:Infant; D008297:Male; D008661:Metabolism, Inborn Errors / Q000097:blood*; D008667:Metalloproteins / Q000378:metabolism*; D008982:Molybdenum / Q000378:metabolism*; D000090006:Molybdenum Cofactors; D011228:Prealbumin / Q000737:chemistry / Q000378:metabolism*; D011621:Pteridines / Q000378:metabolism*; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods*; D013451:Sulfonic Acids / Q000737:chemistry
D003067:Coenzymes; D008667:Metalloproteins; D008982:Molybdenum; D000090006:Molybdenum Cofactors; D011228:Prealbumin; D011621:Pteridines; D013451:Sulfonic Acids; C022261:molybdopterin