Vargulin

Vargulin,^[1] also called Cypridinid luciferin,^[2] Cypridina luciferin, or Vargula luciferin, is the luciferin found in the ostracod Cypridina hilgendorfii, also named Vargula hilgendorfii.^[3] These bottom dwelling ostracods emit a light stream into water when disturbed presumably to deter predation. Vargulin is also used by the midshipman fish, Porichthys.

Vargulin

Names
IUPAC name 2-[3-[2-[(2S)-butan-2-yl]-6-(1H-indol-3-yl)-3-oxo-7H-imidazo[2, 1-c]pyrazin-8-yl]propyl]guanidine
Other names Cypridina luciferin, cypridinid luciferin, Vargula luciferin
Identifiers
CAS Number	7273-34-9
3D model (JSmol)	Interactive image
ChemSpider	388868 N
PubChem CID	135398684
UNII	761TM14Y84 Y
CompTox Dashboard (EPA)	DTXSID40331446
InChI InChI=1S/C22H27N7O/c1-3-13(2)19-21(30)29-12-18(15-11-26-16-8-5-4-7-14(15)16)27-17(20(29)28-19)9-6-10-25-22(23)24/h4-5,7-8,11-13,26-27H,3,6,9-10H2,1-2H3,(H4,23,24,25) Y Key: ZWPWSXGBDMGKKS-UHFFFAOYSA-N Y InChI=1S/C22H27N7O/c1-3-13(2)19-21(30)29-12-18(15-11-26-16-8-5-4-7-14(15)16)27-17(20(29)28-19)9-6-10-25-22(23)24/h4-5,7-8,11-13,26-27H,3,6,9-10H2,1-2H3,(H4,23,24,25)/t13-/m0/s1 Key: ZWPWSXGBDMGKKS-UHFFFAOYAG
SMILES O=C\3N4\C=C(\c2c1ccccc1[nH]c2)N/C(=C4/N=C/3[C@@H](C)CC)CCC/N=C(\N)N
Properties
Chemical formula	C22H27N7O
Molar mass	405.506 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

History

A partial extraction procedure was developed in 1935 which involved reacting the compound with benzoyl chloride to allow it to be separated from the water-soluble components.^[4] The compound was first isolated and purified to crystals by Osamu Shimomura.^[5] The structure of the compound was confirmed some years later.^[6] Feeding experiments suggest that the compound is synthesized in the animal from three amino-acids: tryptophan, isoleucine, and arginine.^[7]

Biochemistry

Vargulin is oxidized by the Vargula luciferase,^[8] a 62 kDa enzyme, to produce blue light at 462 nm (max emission, detected with a 425 to 525 nm filter). The vargulin does not cross react with luciferases using coelenterazine or Firefly luciferin.

Uses

Vargulin (with the associated luciferase) has applications in biotechnology:

• in a variety of assays, to report gene or gene expression after luciferase have been genetically introduced in cells,
• to detect ATP, that is used in the vargulin/luciferase reaction (cell viability assays).^[9]

Although less stable, the Cypridina system is useful because can be used in multiplex assays with other (red-emitting) luciferin assays.