SEPX1, also known as Methionine sulfoxide reductase B1 (MSRB1), is a selenoprotein. Methionine sulfoxide reductases(MSRs) catalyze reduction of free and protein-bound methionine sulfoxides to corresponding methionines. The oxidation of methionine by ROS generates a diastereomeric mixture of methionine-S-sulfoxide (Met-S-SO) and methionine-R-sulfoxide (Met-R-SO). Two distinct enzyme families evolved for reduction of these sulfoxides, with methionine-S-sulfoxide reductase (MsrA) being stereospecific for Met-S-SO and methionine-R- sulfoxide reductase (MsrB) for Met-R-SO. In bacteria, the selenocystein (Sec/U) element is located immediately following the UGA codon within the reading frame for the selenoprotein so we mutated Sec-95 to Cys. Source: Recombinant protein corresponding to aa1-116 from human SEPX1, fused to His-tag at N-terminal expressed in E. coli. Molecular Weight: ~14.8kD (136aa) AA Sequence: MGSSHHHHHH SSGLVPRGSH MSFCSFFGGE VFQNHFEPGV YVCAKCGYEL FSSRSKYAHS SPWPAFTETI HADSVAKRPE HNRSEALKVS CGKCGNGLGH EFLNDGPKPG QSRFCIFSSS LKFVPKGKET SASQGH Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing.. Store at -20C. Aliquots are stable for 6 months after receipt at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.