Cysteine Probe

Cysteine is a semi-essential proteinogenic amino acid with the formula HO2CCH(NH2)CH2SH. The thiol side chain in cysteine is typically involved in the enzymatic reaction as a nucleophile. Mercaptans are easily oxidized to form cysteine, a disulfide bond derivative, which plays an important structural role in many proteins. When used as a food additive, its E number is E920. It is encoded by the codon UGU and UGC. Cysteine has the same structure as serine, but one of the oxygen atoms is replaced by sulfur; replacing it with selenium produces selenocysteine. Like other natural protein amino acids, cysteine has a chirality in the earlier d/l representation based on homology to d- and 1-glyceraldehyde. In the updated chiral R / S system, based on the number of atoms in the atom near the asymmetric carbon, cysteine (and selenocysteine) has R chirality because of the presence of sulfur (or selenium) as the second neighbor of symmetric carbon. The remaining chiral amino acids with lighter atoms at this position have S chirality.

Figure 1. Chemical structure of cysteine.

Biological function

Cysteine thiol groups are nucleophilic and are easily oxidized. When the thiol is ionized, the reactivity is enhanced, and the pKa value of the cysteine residue in the protein is close to neutral, and thus is often present in the cell as its reactive thiolate. Due to the high reactivity of cysteine, its cysteine has many biological functions, so cysteine may play an important role in the development of primitive life on Earth.

Cysteine Probe

Certain thiol-containing amino acids in organisms, such as cysteine and cystine, have important physiological significance in the metabolism of organisms. Cysteine is involved in the process of cell reduction in organisms and regulates phospholipids in the liver. Metabolism and protection of liver cells from toxic damage. Cystine is often distributed in peptide bonds with cysteine residues in proteins, and then forms -SS-bridge bonds to crosslink peptide bonds, thus maintaining certain the spatial configuration of proteins and their biological functions are very important. Therefore, the detection of cysteine is of great importance.BOC Sciences offers a range of high quantum yield and highly photostable probes for rapid detection and quantification of cysteine (Cys) and homocysteine (HCys). Our probes are easy to detect Cys and we can provide highly repeatable results. Our cysteine probes are highly selective probes for the detection and quantification of cysteine (Cys) and homocysteine (HCys), which are readily soluble in aqueous buffers such as PBS (phosphoric acid) Both the salt buffered saline and MeOH or EtOH, the absorption and excitation bands were concentrated at ≈500 nm, increased with time, and increased with increasing concentrations of cysteine (and homocysteine).

Reference:

Weast, Robert C.; et al. CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. 1981, p. C-259.

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