MOSCOW, May 31. /TASS/. Researchers from Krasnoyarsk identified a new luminous substance which is perfectly suitable for creating luminescent labels widely utilized in medicine and science. The results of the study have been published in the journal Photochemistry and Photobiology.

Luminescent labelling is often used in medicine and other sciences. For example, by using the molecules of a luminous substance, one can test new drugs, track tumor growth in lab animals, or monitor the ecological situation. These types of labels are very convenient for usage, they are non-toxic and do not emit radiation which makes them more secure compared to the alternative of radioisotope labels.

The new luminous protein has been extracted from the plankton, maxillopod Metridia longa, living in the White Sea.

In the wild, a maxillopod uses this protein to defend itself from carnivores. It pumps out a cloud of luminous content into the sea and by doing so it distracts carnivores enabling it to escape. In order to emit the light, a protein molecule called luciferase is bound to the molecule of the substrate.

The researchers studied the protein structure and mapped out the mechanism of the molecule’s bioluminescence. To perform the study, they created a mutant form of the protein lacking some amino acids, the structural elements which every protein consists of. Using this approach, the scientists managed to define the role of different amino acids and to clarify that the bonding of protein with a substrate and, consequently, the luminescence takes place in the active center of the molecule due to the interaction of two amino acids - tyrosines.

"The protein which we discovered possesses some very attractive features. This is the smallest protein molecule capable of executing biological luminescence. Additionally, the glow is very bright. This implies that if it is utilized as a label, its presence should not bother a living cell.

To track the luminescence, several molecules should be enough which in turn provides high sensitivity of the analysis. Moreover, this unique protein can sustain extremely high temperatures and can shine also after an hour of boiling," said Marina Larionova, a study coauthor of and PhD student at the Institute of Fundamental Biology and Biotechnology of Siberian Federal University.

The knowledge on the mechanisms of luminescence will enable the assessment of the potential capacity of protein, for changing them for new purposes and hence broadening the range of possible applications.

"Each protein which has been newly-discovered should be carefully studied by means of biochemical approaches as this is of high importance for fundamental science," Larionova added.