Updated project metadata. Missing proteins(MPs) investigation is one of the critical missions of Chromosome-based Human Proteome Project(C-HPP). Through analyzing sequence of MPs from neXtProt database, we found that there are no detectable tryptic peptides for some MPs. Here, we attmept a multi-enzymes strategy to cover this problem. Lys-C, Glu-C and LysargiNase are used to produce more unique and detectable peptides of MPs.