Abstract: Genes all5292 and alr0647 were obtained by BLAST comparison from the cyanobacterium,Anabaena sp.PCC7120.They are homologous to cpcS and cpcT encoding the biliprotein lyases.According to the homology analysis,the similarity of All5292 and CpcS was up to 53.4%,and that of All0647 and CpcT up to 61.4%.The functions of All5292 and Alr0647 were analyzed in vitro with a heterologous E.coli system with plasmids conferring biosynthesis of phycocyanobilin(PCB)and of the acceptor proteins,β-phycoerythrocyanin(PecB)or β-phycocyanin(CpcB).The products were evaluated with absorption spectra and fluorescence spectra.The results showed that no lyase activity was found in any case,although all5292 and/or alr0647 expressed in the heterologous E.coli system.Via analyses of the transcription of all5292 and alr0647 in Anabaena sp.PCC7120,it was found that all5292 and alr0647 were transcribed only under N-starved conditions.