products | fluorescence technology | Fluorescent Labels for Biomolecules

Fluorescence Technology

Fluorescent Labels for Biomolecules

DY-dyes are available with various modifications, e.g. as
carboxylic acid, aminoreactive dyes (N-Hydroxysuccinimidyl-ester), maleimides, amine modified and biotinylated labels.

Avidin- and streptavidin labeled conjugates are available on request.

Please note:
We offer several Starter Kits which contain a selection of labels in sample amounts. Feel free to ask for an individual offer.

Overview on physical data of the DY-Labels

Amine reactive Dyes

Primary amino groups are natural components of peptides and proteins which consist of amino acids. At least one amino group is positioned at the N-terminus of the peptide chain. Other biomolecules can be modified in such a way that an amino group is incorporated without changing its activity or functionality. The most common examples are 5’-aminomodified DNA oligomers and cDNA bearing aminoallyl-dU-units. There are several functional groups which react with primary amino groups forming a covalent bond between amino containing (bio-)molecule and react under mild conditions not harmful to biologically active compounds. The most common reactive group being the NHS-ester (N-Hydroxysuccinimidyl-ester). At a pH between 8 and 9, the NHS-ester reacts specifically with primary amino groups. Depending on the puritiy (content of active NHS-ester) quantitative yields can be achieved.

Please download coupling protocol for proteins

Maleimides

As well as primary amino groups, thiol groups are preferred targets for fluorescent labels. There are various chemical moieties which form stable chemical bounds with thiole groups, including maleimides and iodoacetamides. An advantage over the labeling of amino groups in proteins is the low influence of a neutral thiol-reactive label on the isoelectric point of a protein, making differential 2D-gel electrophoresis possible.

Maleimides couple to thiol groups under very mild conditions at pH around 7.

Performance of DY-631 in 2D-gel elelctrophoresis

Biotinylated labels

These modifications can be used to bind to streptavidin or avidin under physiological conditions, making it easy to detect the above proteins which are widely used in bioanalytics.
	Signals of dye-labeled biotin spots on a streptavidin coated slide

Amine modified Labels

Labels with amino groups can be used for cross coupling to carboxy groups via a mild in situ activation. Amine-modified labels can also be incorporated into a matrix during polymerization.

DY-505-X5- Phalloidin

Green fluorescent phalloidin derivative for selectively labeling F-actin

Phallotoxins (phalloidin and phallacidin) are bicyclic peptides isolated from the deadly Amanita phalloides mushroom. They can be used interchangeably in most applications and bind competitively to the same sites on F-actin. DY-505-X5- Phalloidin is a convenient probe for labeling, identifying and quantitating F-actin in formaldehyde-fixed and permeabilized tissue sections, cell cultures or cell-free experiments.

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