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Inactivation of barley limit dextrinase inhibitor by thioredoxin‐catalysed disulfide reduction
Author(s) -
Jensen Johanne Mørch,
Hägglund Per,
Christensen Hans Erik Mølager,
Svensson Birte
Publication year - 2012
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2012.06.009
Subject(s) - chemistry , cysteine , thioredoxin , thiol , biochemistry , enzyme
Barley limit dextrinase (LD) that catalyses hydrolysis of α‐1,6 glucosidic linkages in starch‐derived dextrins is inhibited by limit dextrinase inhibitor (LDI) found in mature seeds. LDI belongs to the chloroform/methanol soluble protein family (CM‐protein family) and has four disulfide bridges and one glutathionylated cysteine. Here, thioredoxin is shown to progressively reduce disulfide bonds in LDI accompanied by loss of activity. A preferential reduction of the glutathionylated cysteine, as indicated by thiol quantification and molecular mass analysis using electrospray ionisation mass spectrometry, was not related to LDI inactivation. LDI reduction is proposed to cause conformational destabilisation leading to loss of function.