Methionine sulfoxide (MetSO) in calmodulin (CaM) was previously shown to be a substrate for bovine liver peptide methionine sulfoxide reductase (pMSR, EC 126.96.36.199), which can partially recover protein structure and function of oxidized CaM in vitro. Here, we report for the first time that pMSR selectively reduces the D-sulfoxide diastereomer of CaM-bound L-MetSO (L-Met-D-SO). After exhaustive reduction by pMSR, the ratio of L-Met-D-SO to L-Met-L-SO decreased to about 1:25 for hydrogen peroxide-oxidized CaM, and to about 1:10 for free MetSO. The accumulation of MetSO upon oxidative stress and aging in vivo may be related to incomplete, diastereoselective, repair by pMSR. Copyright (C) 1999 Federation of European Biochemical Societies.
Bibliographical noteFunding Information:
This study was supported by the National Institutes of Health (Grant P01AG12993). We thank Todd D. Williams of the KU Mass Spectrometry Laboratory for acquiring the ESI MS spectra, and Drs. J. Moskovitz and R.L. Levine for providing the pMSR clone.
- Hydrogen peroxide
- Methionine sulfoxide
- Oxidative stress
- Peptide methionine sulfoxide reductase