Chemical arrays

Specific differences in toxicity toward each test species were discovered between the various plant chemical arrays. Table HI lists survivorship for these species for alkaloid-producing cacti. Additionally, data was obtained for 20 species in which alkaloids were not detected. The three insect species showed consistent differences in tolerance toward given plant species, with no clear phylogenetic pattern accounting for this. Insects also responded differently to aikaloidal fractions versus triterpenoid glycoside fractions. Alkaloids were found to be generally not toxic to D. 

This approach is highly efficient, as thousands to hundreds of thousands or even millions of compounds can be generated easily. In this review, we shall briefly discuss the preparation of these chemical microarrays and follow with a more detailed discussion on the various screening methods. Applications of these microarrays to various biological systems will also be described. The approaches that have been employed for preparing microarrays and the methods used to detect activity in different applications are summarized in Table 1. Schematic representations of the generation of planar chemical arrays and bead-arrays are shown in Figure 1. DNA and... 

Figure 1 Schematic representation of generation of planar chemical arrays and bead-arrays...

The challenge remains to identify more precisely the specific surface chemical arrays on a foreign material which, when it is inserted into the uterine cavity, might trigger reactions that produce these adverse effects as well as inhibit reproductive activities (23). 

Table 1 Factors Guiding the Design and Automated Synthesis of a Spatially Addressable Chemical Array...

In order to efficiently bioassay large compound arrays while preserving the integrity of the SAR information content of the spatial array, we have found that multiple, parallel, high-throughput bioassays are an attractive alternative. We will review several case examples of multiplexed bioassays with spatially-addressable chemical arrays and discuss issues related to data management, prevention of readout crosstalk and multiplexing of primary and secondary assays. 

It should be noted that chemical array platforms have also been utilized in discovering and analyzing new organic reactions [16,17]. Although these studies include outstanding ideas and successful applications, they are not mentioned in this chapter because these platforms are intended to address different chenfical issues. 

To date, several tactics and strategies have been described for the fabrication of chemical arrays. These strategies can be classified in the following manner based on how small molecules are introduced into the array (1) site-specific covalent immobilization, (2) site-nonspecific covalent immobilization, (3) site-specific... 

Figure 4-5 PNA-encoded self-assembling chemical arrays, (a) Each small molecule was labeled with a PNA tag as well as a fluorophore. (b) The tagged molecules were hybridized with their complementary sequences on a decoding array, (c) Incubation of the tagged molecule library with a protein sample generated a protein-small molecule conjugate, which could be separated by using size-exclusion chromatography. Structural information on the bound small molecule was decoded by the decoding array.

Noncovalent fluorous-based interactions have also been used to construct chemical arrays. The original concept of fluorous-based chemical arrays was demonstrated by Ko et al. with unprotected carbohydrate ligands [67]. Flu-orous tags are originally developed to simplify purification steps during the synthesis of small molecules [68], but they demonstrated the strength of the... 

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