44
V. K. Kannaujiya et al.
2012). PBPs are made up of different colored subunits such as phycoerythrin, phycocyanin and allophycocyanin, and colorless linker polypeptides. Each PBPs subunit
has a characteristic heterodimer linear tetrapyrrole chromophore with four rings (A,
B, C, and D) which covalently attached to thiol linked cysteine residue at C-3 position
in ring A and ring D by C-18 position (Kannaujiya and Sinha 2017a). According to
chromophore absorbance and structure, PBPs are broadly divided into three classes
such as phycocyanin (PC; λ max = 610–620 nm), phycoerythrin (PE; λ max = 560–
570 nm), and allophycocyanin (APC; λ max = 650–660 nm) (Sidler 1994, Kannaujiya
and Sinha 2016a) (Fig. 3.1).
PBPs are made up of two basic heterodimer α and β subunits which aggregate and
functionalize into monomeric, trimeric (αβ) 3 (APC), or (αβ) 6 hexameric conformation (PE, PC). Pathway of energy transfer from solar spectrum is initiated from PE to
PC to APC and ultimately to reaction center for proper carbon fixation during photosynthesis. The molecular structure of PC and APC are embedded on the periphery
and core region of photosynthetic membrane (Singh and Montgomery 2013). PE is
attached at the distal end of PBPs and plays a crucial role in light adaptation (Kannaujiya and Sinha 2016a, b). Most PBPs subunits are made up of hetero-monomer united
by two subunits such as α and β with molecular weight ranging from 12–20 kDa and
15–22 kDa, respectively (Galland-Irmouli et al. 2000).
Cyanobacterium
Fig. 3.1 Chemical structure of phycobiliproteins isolated from cyanobacteria (Adapted and
modified from Kannaujiya et al. 2018)
V. K. Kannaujiya et al.
2012). PBPs are made up of different colored subunits such as phycoerythrin, phycocyanin and allophycocyanin, and colorless linker polypeptides. Each PBPs subunit
has a characteristic heterodimer linear tetrapyrrole chromophore with four rings (A,
B, C, and D) which covalently attached to thiol linked cysteine residue at C-3 position
in ring A and ring D by C-18 position (Kannaujiya and Sinha 2017a). According to
chromophore absorbance and structure, PBPs are broadly divided into three classes
such as phycocyanin (PC; λ max = 610–620 nm), phycoerythrin (PE; λ max = 560–
570 nm), and allophycocyanin (APC; λ max = 650–660 nm) (Sidler 1994, Kannaujiya
and Sinha 2016a) (Fig. 3.1).
PBPs are made up of two basic heterodimer α and β subunits which aggregate and
functionalize into monomeric, trimeric (αβ) 3 (APC), or (αβ) 6 hexameric conformation (PE, PC). Pathway of energy transfer from solar spectrum is initiated from PE to
PC to APC and ultimately to reaction center for proper carbon fixation during photosynthesis. The molecular structure of PC and APC are embedded on the periphery
and core region of photosynthetic membrane (Singh and Montgomery 2013). PE is
attached at the distal end of PBPs and plays a crucial role in light adaptation (Kannaujiya and Sinha 2016a, b). Most PBPs subunits are made up of hetero-monomer united
by two subunits such as α and β with molecular weight ranging from 12–20 kDa and
15–22 kDa, respectively (Galland-Irmouli et al. 2000).
Cyanobacterium
Fig. 3.1 Chemical structure of phycobiliproteins isolated from cyanobacteria (Adapted and
modified from Kannaujiya et al. 2018)