Development of a Solid-Phase Colorimetric Assay for the Screening of Transglutaminase Activities

Abstract

A solid-phase colorimetric assay method for transglutaminase activities has been developed. The principle of the assay is to monitor cross-linking activities between casein bound to microtiter plates and free biotinylated casein by the sample. Quantitation of immobilized biotin-labeled casein formation through the enzymatic reaction was conducted by avidin or streptavidin conjugated enzymes. For this purpose, the efficiency of four different reporter enzymes (streptavidin or avidin conjugated alkaline phosphatase, streptavidin or avidin conjugated horseradish peroxidase) was compared, especially focusing on the sensitivity and specificity of the respective methods. The newly developed assay method was applied to the procedure of transglutaminase C purification from human erythrocytes and proven to have good correlation with conventional C14 putrescine method (r = 0.85, p(0.05). Moreover, since this new method can detect enzymatic activity without use of radioisotope and can process a number of samples simultaneously, it is possible to screen a mass population for transglutaminase deficiency, such as factor XIII, in routine clinical laboratories.