Chloroplast glyceraldehyde-3-phosphate dehydrogenase contains a single disulfide bond located in the C-terminal extension to the B subunit

Mass mapping analysis based on cyanylation and CN-induced cleavage indicate s that the two cysteine residues in the C-terminal extension of the B subun it of the light-activated pea leaf chloroplast glyceraldehyde-3-phosphate d ehydrogenase form a disulfide bond. No evidence was found for a disulfide b ond in the A subunit, nor was there any indication of a second disulfide bo nd in the B subunit. The availability of the structure of the extended glyc eraldehyde-3-phosphate dehydrogenase from the archaeon Sulfolobus solfatari cus allows modeling of the B subunit. As modeled, the two cysteine residues in the extension are positioned to form an interdomain disulfide cross-lin k.