2-NBDG is a fluorescent tracer used for monitoring glucose uptake into living cells; it consists of a

glucosamine Glucosamine (C6H13NO5) is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is part of the structure of two polysaccharides, chitosan and chitin. Glucosamine is one of the most ...

molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

substituted with a 7-nitrobenzofurazan

fluorophore A fluorophore (or fluorochrome, similarly to a chromophore) is a fluorescent chemical compound that can re-emit light upon light excitation. Fluorophores typically contain several combined aromatic groups, or planar or cyclic molecules with se ...

at its

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen Hydrogen is the chemical element wi ...

group. It is widely referred to a fluorescent derivative of

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

, and it is used in cell biology to visualize uptake of glucose by cells. Cells that have taken up the compound fluoresce green. 2-NBDG is similar to

radiolabeled A radioactive tracer, radiotracer, or radioactive label is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tr ...

glucose in that both can be used to detect glucose transport. Unlike radiolabeled glucose, 2-NBDG is compatible with fluorescence techniques such as a fluorescent microscopy, flow cytometry, and fluorimetry The compound is taken up by a variety of

mammalian Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur o ...

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...

, and microbial cells In mammalian cells, one transporter for 2-NBDG is supposed to be

GLUT2 Glucose transporter 2 (GLUT2) also known as solute carrier family 2 (facilitated glucose transporter), member 2 (SLC2A2) is a transmembrane carrier protein that enables protein facilitated glucose movement across cell membranes. It is the principa ...

., but this has been recently challenged (see below). In bacterial cells, the predominant transporter is the

mannose Mannose is a sugar monomer of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several congenital disorders of glycosylation ...

phosphotransferase system PEP group translocation, also known as the phosphotransferase system or PTS, is a distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP). It is known to be a multicomponent system that always i ...

. Cells that lack these or other compatible transporters do not take up 2-NBDG. Like glucose, 2-NBDG is transported according to

Michaelis–Menten kinetics In biochemistry, Michaelis–Menten kinetics is one of the best-known models of enzyme kinetics. It is named after German biochemist Leonor Michaelis and Canadian physician Maud Menten. The model takes the form of an equation describing the rat ...

. However, transport of 2-NBDG has a lower ''V''_max (maximum rate), and thus the rate of transport is generally slower than glucose. Once taken up, the compound is metabolized to a non-fluorescent derivative, as shown in ''

Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...

''. The identity and further metabolism of this non-fluorescent derivative has not been established. Three articles published between 2020 and 2022 indicate that the uptake of 2-NBDG is independent of Glut transporters and as such, it does not reflect true glucose intake like radiolabeled glucose would

References

{{DEFAULTSORT:2-NBDG Hexosamines Deoxy sugars Aldohexoses