CROSS-LINKERS

See also: Protein modifyers - Buffers - Labeling reagents (biotin)

• General Information                          

• Main Biochemicals features of Cross-Linkers    

• Selection guide to Cross-Linkers

• Heterobifunctional

2

3

4

5

6

• Homobifunctional

7

8

9

• Photoreactive

10

11

12

13

General Information

They allow conjugates preparation of molecules gathering the properties (biological activity) of both constituants.

Main biochemical features of Cross-Linkers

Main available and reactive chemical groups present in biomolecules are amines, carboxyls, and sulfhydryls. Uptima offers easy to use reagents to conjugate through theses moieties. Proteins are the frequently chemically modified because they are often easer to handle and known.

The choice of target chemical group is often crucial if it is involved in the researched biological activity of the conjugate : NHS targetting may affect the affinity or specificity of antibodies which epitope is rich in NH2s, maleimide targetting may inactivate Cys-containing catalytic enzymes…

The spacer is the arm separating the 2 reactives groups in the cross-linker. After reaction, it links the 2 conjugated biomolecules, being thus responsible of different properties of the conjugate.

• The lenght of the arm should be considered for the stereoscopic availability during the conjugation step, and then the availability of the conjugated biomolecules for other ligands (receptors, substrates…). A longer spacer is thought often to improve the biological activity of conjugates, for example the enzymes, receptors…

• The nature of the spacer should be to considered for other various purposes : for example,

• the aryl-structure of MBuS was found less immunogenic than the aromatic spacer of MBS.

• linear spacer allow a certain flexibility, hence often better availibility of biomolecules, while constrained structures can either favour or impeach the right orientation of the 2 biomolecules within the conjugate for a given ligand interaction.

Conjugating biomolecules allow to join properties of each molecule, that can act simultaneously or separately. Notably once the conjugate can be useful to allow remove on molecule after it has acted, for example binding the conjugate to a receptor. An efficient way consists to cleave the spacer arm under controlled conditions. Dissulfide link provide a convenient cleavable spacers, because it can be broken by reducing agents like DTT (UP284250) or TCEP (UP242214).

The labeling reagents have different hydrophobic patterns, that generate important incidence in biological applications. For example, lipophilic reagents cross the biological membranes and label both outside and inside biomolecules of cells.

At the opposite, polar reagents should be used if only the out-side exposed proteins should be labelled on cells. Uptima provides for that purpose high quality sulfonated derivatives. An additional advantage is that sulfonated reagents can be added directly in aqueous buffer, eliminating the need of organic solvent that may be undesired or toxic (DMSO).

Selection guide to Cross-Linkers

Cat #

-

Description

Qty

Reactivity

1

Reactivity

2

Spacer

arm

MW

Membrane permeability/

water low solubility

Iodinatable

-

-

-

177,2

-

-

-

-

-

177,2

-

-

SH

NH2

21A

446,6

-

-

SH

NH2

21A

446,6

-

-

NS

Arg

9,3A

193,2

-

-

NS

Arg

9,3A

193,2

-

-

-

-

-

177,2

-

-

-

-

-

249,3

-

-

SH

NH2

-

417,3

-

-

NS

NS

34,7A

474,5

-

thiol cleavable

NS

NS

34,7A

474,5

-

thiol cleavable

NH2

NH2

13,0A

436,3

Yes

Base reversible

NH2

NH2

13,0A

436,3

Yes

Base reversible

NH2

NH2

8,6A

245,1

-

-

NH2

NH2

8,6A

245,1

-

-

DMPI (DMP)

NH2

NH2

9,2A

259,2

-

-

DMPI (DMP)

NH2

NH2

9,2A

259,2

-

-

DMPI (DMP)

NH2

NH2

9,2A

259,2

-

-

NH2

NH2

11,0A

273,2

-

-

NH2

NH2

11,0A

273,2

-

-

SH

SH

19,0A

482,7

-

cleavable

SH

SH

19,0A

482,7

-

cleavable

NH2

NH2

12,0A

404,4

Yes

-

NH2

NH2

11,4A

368,3

Yes

-

NH2

NH2

11,4A

368,3

Yes

-

NH2

NH2

11,4A

368,3

Yes

-

NH2

NH2

-

396,4

-

-

NH2

NH2

--

419,2

Yes

-

NH2

NH2

6,4A

344,2

Yes

-

DTBP

NH2

NH2

-

309,3

-

-

NS

NS

-

300,4

-

v

NH2

COOH

191,7A

-

-

-

NH2

COOH

191,7A

-

-

-

NH2

COOH

191,7A

-

-