Substrate specificity of human matriptase-2

Human matriptase-2 is an enzyme that belongs to the family of type II transmembrane serine proteases. So far there is a limited knowledge regarding its specificity and protein substrate(s). One of the identified natural substrates is hemojuvelin, a protein involved in the control of iron homeostasis. In this work, we describe the synthesis and evaluation of internal quenched substrates using a combinatorial approach. The iterative deconvolution of two libraries to define the specificity of matriptase-2 yielded to the identification of the substrate ABZ-Ile-Arg-Ala-Arg-Ser-Ala-Gly-Tyr(3-NO2)-NH2 with a kcat/Km value of 4.5 × 105 M−1 × s−1, i.e. the highest specificity constant reported so far for matriptase-2.