Kremer Anika, Li Shu-Ming
Heinrich-Heine-Universität Düsseldorf, Institut für Pharmazeutische Biologie und Biotechnologie, Universitätsstrasse 1, D-40225 Düsseldorf, Germany.
Chem Biol. 2008 Jul 21;15(7):729-38. doi: 10.1016/j.chembiol.2008.05.019.
Recently, five indole prenyltransferases from Aspergillus fumigatus have been proven biochemically to be responsible for prenylations of diverse substrates. In this study, we show peptidase activities of 7-DMATS, FgaPT1, CdpNPT, and FtmPT1, with preference for linear peptides containing a tryptophanyl moiety at the N terminus. Testing of 31 peptides revealed that these enzymes shared similar substrate specificity and accepted H-L-Trp-L-Ala-OH and H-L-Trp-Gly-OH as best substrates for aminopeptidase activity. By using H-L-Trp-Gly-OH as substrate, Km values at 350, 380, 300, and 420 microM and enzymatic rate constants kcat/Km at 0.51, 0.24, 0.53, and 0.14 mM(-1)s(-1) were determined for 7-DMATS, FgaPT1, CdpNPT, and FtmPT1, respectively. In contrast to prenyltransferase activities, the aminopeptidase activities were strongly or completely inhibited by EDTA. Mn2+ increased the aminopeptidase activities of FtmPT1 and CdpNPT up to 4- and 6-fold, respectively. To the best of our knowledge, this is the first report on the catalytic promiscuity of prenyltransferases.
最近，来自烟曲霉的5种吲哚异戊烯基转移酶已通过生物化学方法证明可负责多种底物的异戊烯基化。在本研究中，我们展示了7-DMATS、FgaPT1、CdpNPT和FtmPT1的肽酶活性，这些酶优先作用于N端含有色氨酸部分的线性肽。对31种肽的测试表明，这些酶具有相似的底物特异性，并且接受H-L-色氨酸-L-丙氨酸-OH和H-L-色氨酸-甘氨酸-OH作为氨肽酶活性的最佳底物。以H-L-色氨酸-甘氨酸-OH为底物，分别测定了7-DMATS、FgaPT1、CdpNPT和FtmPT1的Km值，分别为350、380、300和420 microM，酶促速率常数kcat/Km分别为0.51、0.24、0.53和0.14 mM(-1)s(-1)。与异戊烯基转移酶活性相反，氨肽酶活性受到EDTA的强烈或完全抑制。Mn2+分别使FtmPT1和CdpNPT的氨肽酶活性提高了4倍和6倍。据我们所知，这是关于异戊烯基转移酶催化多效性的首次报道。
