HTS screens

Library design viewed as a computational process and the experimental implementation of a library design can result 

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It is very important to understand the goal in an HTS screen because the screening goal has a very large impact on what types of compounds should be screened, on how many compounds should be screened, and how much the screening compounds might be expected to cost. 

In order to determine whether compounds identified in the primary HTS screen are specific, a counterscreen is required to identify and eliminate false positives that will arise in the primary screen. For protein—protein interaction screens, it is preferable to test an unrelated protein pair that uses the same mode of detection. For our purposes, we adapted a previously described TR-FRET assay that monitors the interaction between bacterial Staphylococcus aureus Dnal and phage protein 77ORF104 (Liu et al., 2004). 

An important requirement for the successful application of the combinatorial library approach to the drug discovery process, is the ability to utilize the library in high-throughput screening (HTS) procedures. HTS screening of glycopeptide... 

HTS screening is often based on miniaturized cell assays that enable chemical libraries to be screened for molecules that present different biological activities and sometimes-different biological targets using fluorescence, scintillation proximity assays (SPA) and luminescence as detection techniques. 

Reach target PK profile HT-PK profiling and virtual screening Limited in vivo relevance of some HT screens dubious predictive capacity of some statistical models... 

When building HTS screening collections, it has long been the practice not only to proactively select molecules for inclusion but also to deselect compounds that have undesirable properties. Typical deselection criteria are in silico derived chemical reactivity descriptors designed to remove compounds that might give an inappropriate mode of action or result in toxic events [6]. Other properties derived from the molecular... 

Compounds that interfere with the detection mechanism of the HTS assay wiU, in many cases, be detected as highly potent actives [31]. One example would be compounds that intrinsically emit or absorb light at the wavelengths used in a fluorescence-based assay such as fluorescence resonance energy transfer (FRET). In an HTS screen using a fluorescence-based assay at Wyeth, 1.2% of the samples tested showed not just high fluorescence but the maximum possible initial (time 0) reading on the fluorimeter. 

The varying hit rates commonly seen in HTS screens combined with the individual requirements of the project team (stringent or relaxed physiochemical properties, specific scaffolds that represent uninteresting inhibitor classes, and so forth) demand an approach to hit selection that is customizable. This is not true for the Top X method but has been shown clearly here for the current method applied to three very diverse projects with hit rates varying by an order of magnitude (1.3 to 14.6%). 

The selections of compounds are made using a variety of methods, such as dissimilarity selection (16), optiverse library selection (17), Jarvis-Park clustering (18), and cell-based methods (19). All these methods attempt to choose a set of compounds that represent the molecular diversity of the available compounds as efficiently as possible. A consequence of this is that only a few compounds around any given molecular scaffold may be present in a HTS screening... 

Results of Multiple Methods to Model HTS Screening Data and to Then Identify Novel Hits... 

The activities of a compound across screening panels such as a preclinical profiling panel or other protein panels, cell line panels, HTS screening panels, or DNA microarrays can also be a type of signature, termed the biological activity spectra . 

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