Allophycocyanin (APC) is a pigment-protein with optical activity in the core of phycobilisomes of cyanobacteria and red algae. Its wide application prospects make it necessary to carry out the recombinant expression of allophycocyanin with optical activity. In this study, apcA and apcB genes encoding two subunits of allophycocyanin were cloned from Gracilariopsis lemaneiformis. Then apcA and apcB genes expressed in Escherichia coli to obtain allophycocyanin. In order to investigate the active sites of allophycocyanin to bind with phycocyanobilin, the Cys-81 and Cys-138 of α subunit and Cys-81 and Cys-157 of β subunit were mutated. SDS-PAGE and Western blotting results verified the expression of allophycocyanin. The fluorescence emission spectra showed the characteristic fluorescence peak of allophycocyanin, which indicated that the recombinant allophycocyanin had optical activity. The recombinant strains with chromophore lyases—CpcU and CpcS—had the higher fluorescence emission peak, indicating that chromophore lyases would catalyze the combination of phycocyanobilin and apo-allophycocyanin more effectively. The binding sites were Cys-81 and Cys138 of allophycocyanin α subunit, and Cys-81 and Cys-157 of allophycocyanin β subunit. The catalytic effect of CpeT was not obvious. This research provides an experimental foundation for understanding the synthesis mechanism of optically active allophycocyanin in G. lemaneiformis.

藻蓝蛋白（APC）是一种色素蛋白，在蓝细菌和红藻的藻胆体的核心中具有光学活性。其广阔的应用前景使得有必要进行具有光学活性的别藻蓝蛋白的重组表达。在这项研究中，APCA和apcB编码别藻蓝蛋白的两个亚基基因从克隆Gracilariopsis菜。然后在大肠杆菌中表达apcA和apcB基因获得藻蓝蛋白。为了研究别藻蓝蛋白与藻蓝蛋白结合的活性位点，对α亚基的Cys-81和Cys-138以及β亚基的Cys-81和Cys-157进行了突变。SDS-PAGE和Western印迹结果证实了藻蓝蛋白的表达。荧光发射光谱显示了别藻蓝蛋白的特征性荧光峰，表明该重组别藻蓝蛋白具有光学活性。具有生色团裂解酶的重组菌株CpcU和CpcS具有更高的荧光发射峰，表明生色团裂解酶将更有效地催化藻蓝蛋白和脱辅基藻蓝蛋白的组合。结合位点是别藻蓝蛋白α亚基的Cys-81和Cys138，以及别藻蓝蛋白β亚基的Cys-81和Cys-157。CpeT的催化作用不明显。G. lemaneiformis。