DTNB, frequently called Ellman’s Reagent, used as reagent for determination of free sulfhydryl groups. Through reaction with aliphatic thiol groups a mixed disulfide of protein thiol and one mole of 2-nitro-5-thiobenzoate per mole of protein sulfhydryl group is being formed. DTNB has little absorbance. Reaction with -SH groups on proteins (from any solvent accessible Cys) under mild alkaline conditions (pH 7-8) produces the 2-nitro-5-thiobenzoate anion, which gives an intense yellow color with an absorption maximum at 409.5 nm (Extinction coefficient: 14150 M ^-1*cm ^-1). Ellman’s reagent is sensitive to various buffer ions, therefore, the extinction coefficient used to calculate the number of sulfhydryl groups must be matched to the reaction conditions. In case the thiol groups are in disulfide bonds, they must be reduced under anaerobic conditions prior to reaction with DTNB. 
Solubility 8 mg/mL in EtOH. Stock solutions c an be prepared in 0.1 M phosphate buffer, which are stable over several weeks.

Long-chain acylcarnitines are well-known intermediates in mitochondrial fatty acid oxidation

The azido function can be used for different applications

A prominent luciferase group was first discovered in Coelenterata and the corresponding light emitting molecule was therefore named coelenterazine.

Building Blocks for the synthesis of 2,3-diaminobutanoic acid containing peptides or for Click reactions.

Fmoc-Sieber amide resin is an acid-labile carrier for solid phase synthesis of peptide amides. Cleavage can be achieved with only 1% TFA in DCM making them an ideal carrier for the synthesis of protected peptide fragments in fragment condensation strategies for the synthesis of long peptides. It has also been used in organic synthesis of acid-sensitive compounds, for targeted synthesis of primary amines and N-alkylated secondary carboxyamides.

Biotin-PEG Reagent for efficient and smooth capturing and purification of antibody-antigen-complexes.

For antibody labeling via NHS chemistry. Capturing the antibody-antigen complex with streptavidin and isolating of the target protein. Elution of the immune complex from the streptavidin using DTT. Otherwise strong denaturating conditions typically required to break the streptavidin-biotin interaction have to be applied. For very high sensitivity.

Proline derivatives with azido function at position 4 enable Click conjugation just at the edge of a beta-turn. Both optical configurations, 4S and 4R, are available, in order to direct the conjugate specifically in the direction of desire.

Condensation reagent especially suited for coupling of sterically hindered amino acids. Superior suppression of racemization.

Activation AND Protection SIMULTANEOUSLY
A smart technology for avoiding over-alkylation of primary amines

Guanidino groups play an important role in proteolytic digestion of proteins, as they are essential as initial contact between active pockets of for example trypsin and substrates.

Spermines and other Biogenic Polyamines
interact due to their multi cationic structure with DNA!

• Readily applicable to biolabelling, Click 
  conjugation protocols and peptide synthesis
• Stable under buffer conditions (pH 4-8) 
  and in solid phase peptide synthesis
• Broadly applied in cell und animal 
  imaging, tested in FRET systems
• Available in larger quantities compared 
  to e.g. Alexa, Cy-Dyes etc.
• Purities > 85%, supplied as freeze-dried solid powder

alpha-Sulfo-beta-Alanine has been used to couple to hydrophobic labels like Cyanine and Rhodamine dyes and other hydrophobic residues to increase their solubility in water. As di- or tripeptide a further increase of hydrophilicity can be achieved. Fmoc-beta-Ala(SO3H)-OH can be coupled in SPPS by standard phosphonium or uronium based coupling reagents. In high throughput technologies for DNA sequencing and genomics charge-modified dye-labeled dideoxynucleoside-5’-triphosphates were synthesized for ‘direct-load’ applications in DNA sequencing.

Phacm shows the same stability and orthogonality as Acm and has the additional advantage that it can be deprotected simply by water in the presence of PGA. The addition of co-solvents like acetonitrile helps to improve the solubility of hydrophobic sequences. Water in combination with DMSO (80:20) will make deprotection and cyclization a one pot reaction, which is completed (37°C, pH 7) normally within 16h to 24h.

Lipase B from Candida antarctica (EC 3.1.1.3)
adsorbed on hydrophobic polymer Polystyrene DVB cross linked, 300-700µm,
Synthetic Activity >10.000 U/g (dry), 
very high mechanical stability - suitable for packed bed reactors

Reported applications:

Introduction of 9-fluorenylmethyloxycarbonyl, trichloroethoxycarbonyl, and benzyloxycarbonyl amine protecting groups into O-unprotected hydroxylamino acids using succinimidyl carbonates; Anelka Paquet; Can. J. Chem.; 1982; 60: 976.

Widely Applicable Deprotection Method of 2,2,2-Trichloroethoxycarbonyl (Troc) Group Using Tetrabutylammonium Fluoride; Cheng-yuan Huanga; Ning Wanga; Katsumasa Fujikia; Yuji Otsukaa; Masao Akamatsua; Yukari Fujimotoa; Koichi Fukasea; Journal of Carbohydrate Chemistry 2010; 29(6): 289 – 298.

Cleland's reagent, also known as dithiothreitol or DTT is a water soluble protective reagent for sulfhydryl groups.
It reduces disulfide linkages to free sulfhydryl groups in proteins and enzymes.
It is a component of buffers used in protocols for the isolation and purification of proteins.

In our section RESINS/Mercapto Acids/Thiol Resins:

there are Sulphur carrying building blocks linked through Sulphur to different resin supports. In the case of Amino Thiols the side chains are same as in natural proteinogenic amino acids. The amino group is unprotected and free for any coupling steps via standard SPPS protocols, in order to build up a suitable peptide sequence.
 
After cleavage from the resin (with trifluoroacetate using triethylsilane or ethanedithiol as scavenger) a peptide is being designed, which carries a thiol group on the C-terminus. As sulphur has high affinity to heavy metals, like Zn, Fe or Ni, which are essential metal centers in metallo proteins, the affinity of peptide substrates or pharmacological active sequences can further be increased through a strong sulphur-metal interaction.

H-L-Aha-OH*HCl
H-L-Dab(N3)-OH

4-Azido-L-homoalanine
(S)-2-Amino-4-azidobutanoic acid hydrochloride

Formula:                    C4H8N₄O₂*HCl
Molecular Weight:     144,13*35,45 g/mole

CAS:  942518-29-8

CODE:  HAA5730

1g:       EUR    200,-    US$    300,- 
5g:       EUR    800,-    US$  1200,-

Prices are in EUR, net, exw Germany, shipping not include

Mal-AMCHC-OSu

trans-N-Succinimidyl 4-(maleimidomethyl)cyclohexane-1-carboxylate

Formula:                    C16H18N₂O₆
Molecular Weight:     334,33 g/mole

CAS:  64987-85-5

CODE:  MAA1000

1g:       EUR    300,-    US$   420,-
5g:       EUR  1200,-    US$ 1680,-

Prices are in EUR, net, exw Germany, shipping not include