Biocytin

• Nε - ( )- biotinyl -L-lysine
• Biotinyl
• Biotin lysine
• Bct

Beige powder

Fixed

245 ° C.

Template: Infobox chemical / molecular formula search available

Biocytin or epsilon -N-( )- biotinyl -L-lysine is a chemical compound which is one of the carboxamides. With the trivial name biocytin only the compound ( ( ) stereoisomer ), and the L- enantiomer of the amino acid indicated for the vitamin biotin lysine. The carboxyl group of biotin is condensed with the ε - amino group of lysine. As an intermediate product of biotin metabolism occurs biocytin in the blood serum and urine.

Since the late 1980s, is used as a so-called biocytin neuronal tracer as part of histological staining for neurons.

Occurrence and biological significance

Biocytin is the biotin -bearing complex in the following carboxylases meet the basic tasks in carbohydrate, protein and fat metabolism:

• Pyruvate carboxylase
• Methylcrotonoyl -CoA carboxylase
• Propionyl CoA carboxylase
• Acetyl- CoA carboxylase

The degradation of these carboxylases by proteolysis biocytin remains. Cleavage of Biocytins in free biotin and lysine is catalyzed by the enzyme biotinidase. Since animals the vitamin biotin can not produce themselves, they are likely to tap the biotin in the diet and already existing in the body to recycle biotin many times. Therefore constitutes an important biotin Biocytin source for the organism

What significance has biocytin in this regard for the people, biotinidase deficiency is evidenced by the rare genetic disease. Those affected can not adequately utilize and subsequently develop symptoms of biotin deficiency, which can lead to death due to a defect of biotinidase biocytin.

Properties

Biocytin in commercially available form is a beige powder which melts at 245 ° C. How Biotin and biocytin is non-covalently bound avidin.

The enzyme biotinidase hydrolyzes the amide bond of Biocytins formation of biotin and lysine.

Use

Biotinidase test

Biocytin as is the natural substrate of the enzyme biotinidase, it can be used for assaying biotinidase activity. The amount per unit time of the resulting reaction products biotin or lysine is a measure for the activity of the enzyme. For the determination of biotinidase activity in human blood, in particular for the diagnosis of metabolic disorders biotinidase, biocytin, however, is only of limited suitability. The medication with biotin can disguise the enzyme defect.

Neural tracer

Loading with biocytin is a make visible of the many ways neurons including their widely ramified foothills. It is thereby possible to apply biocytin into living tissue, where it is distributed within hours of the nerve cells. Individual neurons can be filled with biocytin by microinjection. After this step, namely, the neurons are selected, but not stained as biocytin itself is not a dye. The coloring of the adhering Biocytins takes place after washing and fusing procedure on cross-sectional specimen. It utilizes the fact that the protein avidin as biocytin binds very strongly to biotin and biotin compounds. One can for example biotinylate a fluorescent dye and then let dock with avidin. Since avidin has multiple binding sites for biotin structures of avidin -fluorophore complex can attach itself to the nerve cell markiernde biocytin his turn - fluoresces the cell. A further possibility is to have an avidin - peroxidase complex to dock with the biocytin. However, this is not yet colored. A Färbevariante consists in a reaction of the peroxidase with diaminobenzidine (DAB ), hydrogen peroxide and divalent nickel and / or cobalt ions.

As the two examples show the use of biocytin to label neurons, the actual staining can be handled very flexible. Thus it is possible to prepare suitable preparations for light microscopy, fluorescence microscopy and electron microscopy.

Safety

Information on the toxicity as well as R- and S -phrases are not currently available for biocytin, the substance is not yet fully tested. Concerning Directive 67/548/EEC of this substance is not classified as hazardous. When working with the pure substance is generally customary precautions are recommended. Due to manufacturer self-classification itself is biocytin in water hazard class (WGK ) 3