Kinetic characterization of a peptide inhibitor of trypsin isolated from a synthetic peptide combinatorial library

Recently Eichler and Houghten1 have described the use of a combinatorial peptide library to optimize small trypsin inhibitors. Our kinetic analysis of the most inhibitory peptide, YYGAKIYRPDKM, reveals that it is an inefficiently cleaved substrate for trypsin due to a low kcat. possesses a relatively low KM, and may exhibit nonproductive binding.