Mutants of HheC and HheG were analyzed in epoxide ring opening of glycidyl phenyl ether (4) using azide, nitrite, cyanide, cyanate, thiocyanate as well as chloride and bromide as nucleophiles. Each 1 mL reaction contained 10 mM epoxide 4, 20 mM nucleophile and 150 µg of purified enzyme in 50 mM Tris•SO4 buffer, pH 7.0. Reactions were carried out at 22 °C (HheG and its mutants) or 30 °C (HheC and its mutants) with shaking at 900 rpm in an Eppendorf ThermoMixer C. Samples were taken after 1 h and 24 h, extracted with an equal volume of tert-butyl methyl ether containing 0.1% (v/v) n-dodecane as internal standard. Organic phases were dried over MgSO4 and samples were analyzed by achiral GC (see Table for details regarding temperature programs and retention times).