Site-directed Mutagenesis of the CpeS of Phycocyanin and Study on the Function with Reconstitution in vivo

To study the structure-function relationships and the effect of the tryptophan residues to the CpeS of phycocyanin,two mutants,CpeS(W14I) and CpeS(W75S),were constructed.The lyase activity of these mutants were tested by reconstitution in vivo,to study the effects of tryptophans to CpeS.The results shows that:CpeS(W14I) has hardly lyase activity.Comparing with the wild CpeS,the lyase activity of CpeS(W14I) and CpeS(W75S) is respectively 8% and 76%.From this,it’s deduced that:the 14th tryptophan residue in CpeS may be essential amino acid to CpeS,and it may locate in the active site of CpeS.