GSTA4, also known as glutathione S-transferase A4, belongs to the GST superfamily. This enzyme is involved in cellular defense against toxic, carcinogenic, and pharmacologically active electrophilic compounds. GSTA4 shows very high activity with reactive carbonyl compounds such as alk-2-enals. GSTA4 is highly effective in catalyzing the conjugate addition of reduced glutathione to 4-hydroxynonenal, an important product of peroxidative degradation of arachidonic acid and a commonly used biomarker for oxidative damage in tissue. This enzyme is expressed at a high level in brain, placenta, and skeletal muscle and much lower in lung and liver. Source: Recombinant protein corresponding to aa1-222 from human GSTA4, fused to His-tag at N-terminal expressed in E. coli. Molecular Weight: ~28.3kD (246aa) Specific Activity: ~4000 pmol/min/ug, and is defined as the amount of enzyme that conjugate 1umole of 1-chloro-2,4- dinitrobenzene (CDNB) with reduced glutathione/minute at pH 6.5 at 25C. Activity Assay: 1. Prepare a 180ul assay buffer into a suitable container. The concentrations are 106mM potassium phosphate (pH6.5), 1.1mM EDTA, 5.5mM glutathione, reduced, 2.2mM 1-chloro-2,4-dinitrobenzene (CDNB), 8% (v/v) ethanol. 2. Equilibrate to 25C and monitor at A340nm until the value is constant using a spectrophotometer. 3. Add 20ul of recombinant GSTA4 protein 40ug/ml in assay buffer. 4. Mix by inversion and record the decrease at A340nm for approximately 5 minutes. Amino Acid Sequence: MGSSHHHHHH SSGLVPRGSH MGSHMAARPK LHYPNGRGRM ESVRWVLAAA GVEFDEEFLE TKEQLYKLQD GNHLLFQQVP MVEIDGMKLV QTRSILHYIA DKHNLFGKNL KERTLIDMYV EGTLDLLELL IMHPFLKPDD QQKEVVNMAQ KAIIRYFPVF EKILRGHGQS FLVGNQLSLA DVILLQTILA LEEKIPNILS AFPFLQEYTV KLSNIPTIKR FLEPGSKKKP PPDEIYVRTV YNIFRP 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.
