Clinical Chemistry 1988-11-01

Assay of dipeptidyl peptidase IV in serum by fluorometry of 4-methoxy-2-naphthylamine.

S Scharpé, I De Meester, G Vanhoof, D Hendriks, M van Sande, K Van Camp, A Yaron

Index: Clin. Chem. 34(11) , 2299-301, (1988)

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Abstract

A new fluorometric assay for determining dipeptidyl peptidase IV (DPP IV; EC 3.4.14.5) was developed. The synthetic substrate glycyl-L-proline-4-methoxy-2-naphthylamide (20 mmol/L), Tris buffer (50 mmol/L, pH 8.3), and serum (20 microL) are mixed and incubated. The reaction is stopped with citrate (100 mmol/L, pH 4.0) and the released 4-methoxy-2-naphthylamine is measured fluorometrically. The mean value of DPP IV activity in serum for 64 healthy subjects was 58 (SD 16) mumol of 4-methoxy-2-naphthylamine released per liter of serum per minute. The proposed procedure is sensitive, rapid, and accurate and can easily be automated.