BackgroundMatrix metalloproteinase 1 (MMP1) has been shown as a novel unique biomarker of bladder cancer in urine. MMP1 can only be detected using conventional and time‐consuming methods, such as ELISA and Western. Refolded MMP1 has been achieved and used in probe screen for many years, while there is no clinical application for MMP1 detection until now. Soluble expression of MMP1 is necessary in urine detection.MethodscDNA of MMP1 has been isolated from human embryonic kidney 293(HEK293) cells. The catalytic domain of MMP1 is expressed as fusion protein with Escherichia coli thioredoxin (TrxA). The 30 kDa recombinant proteins were purified by Ni‐chelating chromatography. The activity of soluble MMP1 was determined and compared with refolded MMP1 by zymography.ResultsCompared with refolded MMP1, TrxA can increase the solubility of MMP1. The soluble MMP1 has the same protein sequences with refolded MMP1 and increased 1.54‐fold of gelatin‐degradation activities than refolded MMP1.ConclusionSuccessfully soluble expression of MMP1 has been achieved by fusion expression and will make progress in discovering specific molecular probes against MMP1.