APC (Allophycocyanin)

Phycobiliproteins are composed of many subunits, each of which has a protein skeleton, with which linear tetrapyrrole chromophores are covalently bound. Phycoerythrin (red) and phycocyanin (blue) are two main phycobiliproteins. The absorption maximum of phycoerythrin (PE) is between 490 and 570 nm, while that of phycocyanin (PC) is between 610 and 665 nm. Generally speaking, phycobiliproteins have good long-term stability when stored in a solution containing ammonium sulfate. The purified phycobiliprotein may decompose into subunits under acidic or alkaline conditions, but it is relatively stable in neutral solution at room temperature when the concentration is greater than 0.1 mg/ml. Dissociated subunits usually have lower coloring and fluorescence than natural pigments. It is suggested that all phycobiliproteins and their conjugates (preferably in neutral buffer solution) should be stored in cold storage and cannot be frozen.