Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.9 (enterokinase)
 675 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adenoregulin is a 33 amino acid antimicrobial peptide isolated from the skin of the arboreal frog Phyllomedusa bicolor. Natural adenoregulin is synthesized with an amidated valine residue at C-terminus and shows lethal effects against filamentous fungi, as well as a broad spectrum of pathogenic microorganisms. A synthetic gene for adenoregulin (ADR) with an additional amino acid glutamine at C-terminus was cloned into pET32a vector to allow expression of ADR as a Trx fusion protein in Escherichia coli BL21(DE3). The resulting expression level of the fusion protein could reach up to 20% of the total cell proteins. The fusion protein could be purified effectively by Ni2+-chelating chromatography. Released from the fusion protein by enterokinase cleavage and purified to homogeneity, the recombinant ADR displayed antimicrobial activity similar to that of the synthetic ADR reported earlier. Comparing the antimicrobial activities of the recombinant adenoregulin with C-amidated terminus to that without an amidated C-terminus, we found that the amide of glutamine at C-terminus of ADR improved its potency on certain microorganisms such as Tritirachium album and Saccharomyces cerevisiae.
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PMID:Expression and purification of antimicrobial peptide adenoregulin with C-amidated terminus in Escherichia coli. 1576 83

Posttranslational modifications influence the structure, stability and biological activity of proteins. Most of the reactions are enzyme-catalyzed, but some, such as asparagine (Asn) and glutamine (Gln) deamidation and the isoaspartate (isoAsp) formation within peptide chains, occur spontaneously. It has been previously shown that certain peptide sequences form isoAsp quite fast if the Asp stretches are exposed to the protein surface, thereby potentially changing susceptibility to proteolysis at these sites. This tempted us to investigate the activity of exo- and endopeptidases against Asp- or isoAsp-containing substrates. Members of the prolyl oligopeptidase family were unable to cleave substrates after proline if isoAsp was placed in the P2-position. Caspases, usually accepting Asp at P1-position of their substrates, did not cleave isoAsp-containing sequences. Similarly, the metal-dependent aminopeptidase amino peptidase N did not turnover N-terminal isoAsp-containing substrates, nor could the endopeptidase matrix metalloproteinase 3 (MMP 3) hydrolyze a serum amyloid A protein-like substrate if the sequence contained isoAsp instead of Asp. Also, the highly specific enterokinase, usually clipping after a stretch of four Asp residues and a lysine in the P1 position, could not turnover substrates if the P2 amino acid was replaced by isoAsp. In contrast, acylamino acid-releasing enzyme and dipeptidyl peptidases 1, 2 and 4 hydrolyzed substrates containing the isoAsp-Ala motif.
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PMID:Isoaspartate residues dramatically influence substrate recognition and turnover by proteases. 1897 29