dtnb

DTNB (Ellman’s Reagent) is used to quantify the number or concentration of thiol groups in a sample. It also can be used for measuring low-molecular-mass thiols such as glutathione in both pure solutions and biological samples.such as blood.

Thioester analogs of glycerophospholipids, in combination with Ellman's reagent, are convenient colorimetric substrates for the measurement of phospholipase (PL) activity. Palmitoyl thio-PC is a chromogenic PLA2 substrate that contains a palmitoyl thioester at the sn-2 position of the glycerol backbone. Hydrolysis of the thioester by PLA2 yields a free thiol that reacts readily with DTNB (Ellman's reagent) giving a bright yellow product with an absorbance maximum at 412 nm. Palmitoyl thio-PC has been used to measure bee venom sPLA2 activity in a phospholipid:Triton X-100 mixed micelle system.

Arachidonoyl Thio-PC is a substrate for many phospholipase A2s (PLA2s) including sPLA2, cPLA2, and iPLA2. Cleavage of the sn-2 fatty acid by PLA2 results in generation of a free thiol which reacts with chromogenic reagents such as DTNB (Ellman's reagent) and DTP to allow quantitation of PLA2 activity. Isozyme-specific cPLA2 activity can be measured by excluding or inhibiting sPLA2 and iPLA2 activities in the assay.

Diheptanoyl Thio-PC is a substrate for all phospholipase A2s (PLA2s) with the exception of cPLA2 and PAF-acetyl hydrolase (PAF-AH). Interaction of this compound with a PLA2 results in cleavage of the sn-2 fatty acid generating a free thiol on the lysophospholipid. This free thiol can be detected using chromogenic substrates such as DTNB (Ellman's reagent) and DTP.