Peptide herbicide-binding

Trebst, A. (1986). The topology of the plastoquinone and herbicide binding peptides of photosystem II in the thylakoid membrane. Z Naturforsch. Sect. C Biosci., 41 240-245. 

Fig. 9. Binding of quinones QAand Qb and the nonheme iron atom to four histidines of the D1 and D2 subunits of photosystem II, based on the amino-acid sequence homology and the crystal structure of the bacterial reaction center. See text for discussiori. Figure (C) adapted from Trebst (1986) The topology of the plastoquinone and herbicide binding peptides of photosystem II In the thylaKoid membrane. Z Naturforsch 41C 243.

Figure 10.6 gives a schematic representation of the essential atoms of a herbicide binding to the 32 kDa peptide of photosystem II, indicating the sp hybrid with X (usually O, S or C) attached to a lipophilic group and the essential positive charge. 

Sensitivity The limit of detection for a certain compound is determined by its affinity constant or binding constant to the interaction partner immobilized to the surface. Therefore, the choice of the capture compound affects remarkably the assay performance. Because of the opportunity to create antibodies against different kind of compounds, e.g., peptides, proteins, enzymes, vitamins, environmental pollutants, herbicides, fungicides, etc., they are frequently used as a versatile tool for sensor assay developments. 

Azidoatrazine ([ " C]-2-azido-4-ethylamino-6-isopropylamino-s-triazine), a derivative of herbicide atrazine which binds to the secondary plastoquinone electron-acceptor site of photosystem 2 (PS2), was used for photoafiinity labeling followed by sequence analysis of peptides derived by proteolysis of the PS2 centers [110]. 

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