Methods for enzymatic and colorimetric determinations of D-erythrulose (D-tetrulose)

The specific determinations of D-erythrulose by enzymatic assay or colorimetric method, which permit the quantitative determination of between 20 and 400 nmol of the sugar, are described. Enzymatic determination of D-erythrulose made use of the D-erythrulose reductase purified from beef or chicken liver, which catalyzes specifically the reduction of D-erythrulose with concomitant conversion of NADH to NAD+. The colorimetric microdetermination of erythrulose could be carried out by utilizing the phenol-sulfuric acid reaction under low temperature. These methods are simple, rapid, and sensitive, and give reproducible results.