DETECTION OF CLEAVAGE OF A PRENISIN-MIMICKING DECAPEPTIDE BY LACTOCOCCUS-LACTIS SUBSP LACTIS ENDOPROTEINASE ACTIVITY

As part of ongoing studies in the biosynthesis of the lantibiotic nisi n, we investigated the proteolytic cleavage of a synthetic Fmoc-labele d decapeptide mimicking a key amino acid sequence of the precursor pre nisin in extracts of a Lactococcus lactis subsp. lactis strain. Revers e-phase high-performance liquid chromatography with photodiode army de tection was used to trace and purify potential enzymatic conversion pr oducts. Of the three newly appearing chromatographic peaks, one was id entified by means of electrospray mass spectrometry, amino acid analys is. and amino acid sequencing as an Fmoc-labeled hexapeptide derived f rom cleavage at the Arg(-1)-Ile(+1) bond. This assay will be useful to monitor the purification of the endoproteinase that reportedly cleave s prenisin at the same Arg(-1)-Ile(+1) site present in the model subst rate.