... Abstract The ATP-reagent, including mutant thermostable Luciola mingrelica firefly luciferase, luciferin, MgSO 4 , buffer components and stabilizers are widely used to assay nano- and picomolar concentrations of adenosine-5 -triphosphate (ATP) in various biological samples. The aim of this study was to estimate activity, stability and analytical characteristics of the ATP-reagent in water and gelatin solutions and in gelatin gel. ... Moscow University Chemistry Bulletin . 2012, Vol. ...