Physics and chemistry of bioluminescence - Rajeev Ranjan, PhD

Firefly bioluminescence system (Fluc: EC 1.13.12.7)

Renilla luciferase (Rluc: EC 1.13.12.5)

•Catalyzes oxidation of Luciferin (Coelenterazine: Imidazopyrazinones (a combination of 5- and 6-membered nitrogen containing rings-structural motifs)

•In the presence of calcium ions to yield oxyluciferin (Oxidized Coelenterazine), CO2 and light (λmax: ≈ 480 nm)

•EC 1. Oxidoreductase (A– + B → A + B–)

•EC 1.13. Incorporation of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2

•EC 1.13.12. Incorporation of one atom of oxygen atom into the other donor

•EC 1.13.12.5 Renilla-luciferin 2-monooxygenase

•Phylum: Cnidaria, Class: Anthozoa, Family: Renillidae, Species: Renilla reniformis

•Luciferin is bound to a luciferin-binding protein (BP-LH2)

Gonyaulax luciferase (LCF: EC 1.13.12.18)

•Lingulodinium polyedrum (formerly known as Gonyaulax polyedra), emits blue-light flashes (λmax: 475 nm) after mechanical or electrical stimulation

•Single protein with three luciferase domains, change in H+ ion concentration causes the luciferase to change conformation

•Catalyzes oxidation of luciferin (Open tetrapyrrole), similar to chlorophyll

•EC 1.13.12.18 Dinoflagellate-luciferin:oxygen132-oxidoreductase

Light is emitted from scintillons (specialized organelles)

Three components required for light emission: luciferase (LCF) , its tetrapyrrole substrate, called dinoflagellate luciferin (LH2) and luciferin binding protein (LBP)

Full-length LCF and each of the individual domains are most active at pH 6.3, and there is very little activity at pH 8.0.

LBP binds luciferin at pH 8.0 but not at pH 6.3 Scintillon acidification: Luciferin is released for reaction with an activated LCF

Gaussia luciferase (Gluc: EC 1.13.12.6)

•Catalyzes oxidation of luciferin (Coelenterazine)

•EC 1.13.12.6 Gaussia-luciferin 2-monooxygenase

•Phylum: Arthropoda, Sub-phylum: Crustacea, Subclass: Copepoda, Family: Metridinidae, Genus: Gaussia, Species: Gaussia princeps

•Gaussia luciferase (GLuc; 185 aa, 19.9 kDa) is the smallest luciferase known and is naturally secreted

•This luciferase emits light at a peak of 480 nm

Metridia luciferase (Mluc: EC 1.13.12.6)

•Bioluminescence in M. longa may well serve as a defense mechanism against predators

•Catalyzes oxidation of luciferin (Coelenterazine)

•EC 1.13.12.6 Metridia-luciferin 2-monooxygenase

•Phylum: Arthropoda, Sub-phylum: Crustacea, Subclass: Copepoda, Family: Metridinidae, Genus: Metridia, Species: Metridia longa

•Luciferase originates as a secretion from epidermal glands in response to various stimuli

•This luciferase emits light λmax: 480 nm

•219-amino acid polypeptide with a molecular weight of 23,885 Da

Vargula/cypridina luciferase (Vhl: EC 1.13.12.6)

•Catalyzes oxidation of luciferin (Coelenterazine)

•EC 1.13.12.6 Vargula-luciferin 2-monooxygenase

•Phylum: Arthropoda, Sub-phylum: Crustacea, Class: Ostracod, Family: Cypridinidae, Genus: Vargula, Species: V. hilgendorfii

•Luciferase originates as a secretion from epidermal glands in response to various stimuli

•This luciferase emits light λmax: 480 nm