Msr-Ratio

• CAT Number: I045001
• CAS Number: 2290635-22-0
• Molecular Formula: C18H14O3S
• Molecular Weight: 310.37
• Purity: ≥95%
• Synonyms: 2-[(E)-2-(4-methylsulfinylphenyl)ethenyl]chromen-4-one
• InChI: InChI=1S/C18H14O3S/c1-22(20)15-10-7-13(8-11-15)6-9-14-12-17(19)16-4-2-3-5-18(16)21-14/h2-12H,1H3/b9-6+
• InChIKey: ICJBRZQQFOCOJU-RMKNXTFCSA-N
• SMILES: CS(=O)C1=CC=C(C=C1)/C=C/C2=CC(=O)C3=CC=CC=C3O2

Msr‑Ratio (Cat No.:I045001) is a ratiometric fluorescent probe designed for methionine sulfoxide reductase (Msr) activity detection both in vitro and in live cells. It is activated by enzymatic reduction of a methyl sulfoxide group to methyl sulfide, switching its emission from ~430 nm to ~550 nm and yielding an approximate 400‑fold fluorescence ratio change (F₅₅₀/F₄₃₀). With excitation at 375 nm and green emission at 550 nm, it offers a large Stokes shift (~120 nm) and achieves saturation in under 30 minutes upon enzyme exposure. In live HL‑60 cells (10 µM), background signal is minimal and fluorescence increases steadily over ~8 hours, demonstrating high specificity and low interference.