Since this molecule is a modified non-typical amino acid it contains an amino group that allows the analysis with the help of standard amino acid analysis or pre- or post-column derivatization prior to the analysis using HPLC-UV or DAD detection. In addition, the non-derivatized amino acid me be detected using liquid-chromatography mass-spectrometry based methods as well.
Acivicin [(2S)-Amino[(5S)-3-chloro-4,5-dihydro-1,2-oxazol-5-yl]ethanoic acid]; molecular formula: C5H7ClN2O3; molar mass: 178.57 g mol−1.
Williams et al. in 2009 solved the crystal structure of the acivicin-modified H.pyloriγ-glutamyltranspeptidase (HpGT). The structure of acivicin-modified HpGT suggests the nucleophilic attack of Thr 380 Oγ at the C3 of acivicin and the displacement of chloride. Furthermore, the researchers report that the integrity of the dihydroisoxazole ring is likely maintained during the reaction since C3 retains its sp2 hybridization. The observed unique C-terminal capping of the active site within the acivicin-modified HpGT structure, together with mutagenesis studies, demonstrated that Phe 567 contributes to the overall catalytic efficiency of the enzyme. The researcher examined the contributions of residues within the C-terminal domain of the 20 kDa subunit and found that local structural motifs are critical for optimal enzymatic activity and autoprocessing. These new insights into the HpGT structure and function relationships are proposed to help facilitate the design of future selective γGT inhibitors. Figure 1 depicts the structure model of the acivicin-inhibited γ-glutamyltranspeptidase (γ-GT).
Figure 1: Structure model of the acivicin-inhibited γ-glutamyltranspeptidase (γ-GT). (Left) The domain structures are highlighted in different colors. (Middle) The secondary structures are highlighted in different colors. (Right) The structure of acivicin is shown and its location inside the protein binding pocket is indicated by the red arrow.
References
Poster DS, Bruno S, Penta J, Neil GL, McGovren JP.; Acivicin. An antitumor antibiotic. Cancer Clin Trials. 1981 Fall;4(3):327-30.
Williams K, Cullati S, Sand A, Biterova EI, Barycki JJ.; Crystal structure of acivicin-inhibited gamma-glutamyltranspeptidase reveals critical roles for its C-terminus in autoprocessing and catalysis. Biochemistry. 2009 Mar 24;48(11):2459-67. doi: 10.1021/bi8014955.