Cupiennins are a group of small

cytolytic Cytolysis, or osmotic lysis, occurs when a cell bursts due to an osmotic imbalance that has caused excess water to diffuse into the cell. Water can enter the cell by diffusion through the cell membrane or through selective membrane channels ...

peptides from the venom of the wandering spider '' Cupiennius salei''. They are known to have high

bactericidal A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance which kills bacteria. Bactericides are disinfectants, antiseptics, or antibiotics. However, material surfaces can also have bactericidal properties based solely on their ...

, insecticidal and haemolytic activities. They are chemically cationic α-helical peptides. They were isolated and identified in 2002 as a family of peptides called cupiennin 1. The sequence was determined by a process called Edman degradation, and the family consists of cupiennin 1a, cupiennin 1b, cupiennin 1c, and cupiennin 1d. The amino acid sequences of cupiennin 1b, c, and d were obtained by a combination of sequence analysis and mass spectrometric measurements of comparative tryptic peptide mapping. Even though they are not strong toxins, they do enhance the effect of the spider venom by synergistically enhancing other components of the venom, such

CSTX CSTX (for "'' Cupiennius salei'' toxins") is a name given to a group of closely related neurotoxic peptides present in the venom of the wandering spider ''Cupiennius salei''. There are twenty types so far described for this protein group. However, s ...

Chemical property

All cupiennins are composed of 35 amino acid residues and are characterised by a more hydrophobic N-terminal chain region and a C-terminus composed preferentially of polar and charged residues. Their distinguishing feature is the absence of

cysteine Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, sometime ...

. On the basis of the absence or presence of

proline Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the prot ...

, cupiennins are divided into two families cupiennin 1 family and cupiennin 2 family.

Cupiennin 1 family

Cupiennin 1 family is the more well-known group, and consists of at least four peptides, such as cupiennin 1a, 1b, 1c, and 1d. Cupiennin 1a (M-ctenitoxin-Cs1a) is the most abundant and has a molecular mass of 3798.63 Da. Cupiennin 1b is less abundant and has a size of 3800.25 Da. Cupiennin 1c (3769.75 Da) and 1d (3795.13) are in extremely low concentrations. These peptides are highly cationic, made up of similar amino acids, but different in the N- and C-terminal ends. The hydrophobic N-terminal is characterised by six repeats of four amino acids, which are in a conserved sequence: position 1 is always

lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. It contains an α-amino group (which is in the protonated form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −C ...

; position 2 is variable; position 3 is always a hydrophobic amino acid or glycine, and in position 4 is either alanine or valine. All members have high antibacterial activity against Gram-positive as well as Gram-negative bacteria at a range of 0.16 to 5 mM concentration. They also exhibit a cytolytic activity between 14.5–24.4 mM on human erythrocytes. They also have

antiprotozoal Antiprotozoal agents ( ATC code: ATC P01) is a class of pharmaceuticals used in treatment of protozoan infection. A paraphyletic group, protozoans have little in common with each other. For example, ''Entamoeba histolytica'', a unikont eukaryotic ...

activity against '' Trypanosoma cruzi'' and

malarial parasite ''Plasmodium'' is a genus of unicellular eukaryotes that are obligate parasites of vertebrates and insects. The life cycles of ''Plasmodium'' species involve development in a blood-feeding insect host which then injects parasites into a verteb ...

. They are insecticidal, but not as strong as the CSTX-1, another peptide of the same venom. These properties are modulated by the

N-terminus The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...

Cupiennin 2 family

Cupiennin 2 family is less well understood, but it also comprises at least four peptides. In fact, members of this family were discovered earlier in 1994 as member of the CSTX peptides. Upon the discovery of cupiennin 1 family, CSTX-3, -4, -5, and -6 are reclassified as cupiennins. This is because of their basic chemical similarities, such as the amino acid residues. They are characterised by the presence of at least one proline. Cupiennin 2a is the best studied. It has a molecular mass of 3701.05 Da, and shows weak cytolytic, bactericidal and insecticidal activities.

References

{{Reflist

External links

UniProtCupiennin 1a at Comparative Toxicogenomics DatabaseCupiennin 1d at Comparative Toxicogenomics Database
Spider toxins Antimicrobials Insecticides