Joe Olechno 1 , Sean Ekins 2 , Antony Williams 3 , Rich Ellson 1 Pittcon 2013 Session 2670 3:55 PM, March 21, 2013 Liquid Handling Processes Impact Computational Modeling in Drug Discovery 1. Labcyte Inc. 2. Collaboration in Chemistry 3. Royal Society of Chemistry
30
Embed
Liquid Handling Processes Impact Computational Modeling in Drug Discovery
The introduction of new pharmaceutical drugs has slowed while money and effort expended by the industry has dramatically increased. We suggest that some of that effort may be inadvertently wasted in drug screening and quantitative structure-activity relationship studies where results can be strongly skewed by the method of liquid handling and the protocol used.
Recent work has demonstrated that dispensing processes have a profound influence on estimates of IC50. What appear to be minor modifications in the design of concentration gradients coupled with long-standing liquid handling procedures have generated a 1.5 to 1,000-fold difference in IC50 showing no correlation or ranking between competing processes. Importantly when such data are used for computational modeling, the computed pharmacophores for each dataset are different and lead to the development of compounds with significantly different structures and chemico-physical properties. Dispensing processes are therefore an important source of error that impacts computational and statistical results. At the same time, commonly-used protocols can generate data can introduce errors independent of the dispensing technology. This paper is an overview of some of the experiences of the authors based on using online chemical compound databases, and publically available data.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Joe Olechno1, Sean Ekins2, Antony Williams3, Rich Ellson1
Pittcon 2013Session 26703:55 PM, March 21, 2013
Liquid Handling Processes Impact Computational Modeling in Drug Discovery
1. Labcyte Inc.2. Collaboration in Chemistry3. Royal Society of Chemistry
•What is Acoustic Liquid Handling?
•Serial Dilutions vs. Direct Dilutions
•Lead Optimization and Pharmacophores
•The Impact of Serial Dilutions on Drug Discovery
•Conclusions
Agenda
2
3
Acoustic Droplet Ejection (ADE)
Comley J, Nanolitre Dispensing, Drug Discovery World, Summer 2004, 43-54
– No cross-contamination– No leachates– No binding
Acoustic Droplet Ejection (ADE)
Acoustic energy expels droplets without physical contact
0
2.5
5.0
7.5
10.0
12.5
15.0
0.1 1 10 100 1000 10000Volume (nL)
%CV
Comley J, Nanolitre Dispensing, Drug Discovery World, Summer 2004, 43-54
•What is Acoustic Liquid Handling?
•Serial Dilutions vs. Direct Dilutions
•Lead Optimization and Pharmacophores
•The Impact of Serial Dilutions on Drug Discovery
•Conclusions
Agenda
5
Conventional Dose-Response Set-up by Serial Dilution
Assay Plate
Intermediate Buffer Dilution Plate
Source Plate
7
Serial Dilution vs. Direct DilutionSerial with Tips Direct with Acoustics
• Equal volumes of changing concentrations
• Errors are compounded
• Compounds are sequentially diluted. Each new dilution is the source for the next step.
• Many “touches” with tips (or significant potential for carry-over or leachates)
• Touchless—no carry-over, leachates or binding
No solute lost
• Low-volume assays with low solvent concentration
• Maximum of one dilution step
• Changing volumes of equal concentrations
• Reduced errorSerial Dilution
Direct Dilution• Low-volume assays with high solvent concentration (or compound loss)
Direct Dilution Process
Third StepTransfer 75, 25,
7.5 and 2.5 nL of each hit to four consecutivewells
Source Plate Assay Plate
Intermediate Plate
First StepTransfer 252.5and 2.5 nL to two wells in an intermediate plate
Second StepDilute intermediateplate with 25 mL DMSO in each well
Fourth StepTransfer 75, 25, 7.5 and 2.5 nL of each dilutedsample to four consecutive wells of the assay plate(30, 10, 3 and one droplets, respectively)
OBoth compounds bind strongly to the GABAA receptor.
These compounds are extremely different in structure but both have the same effect. Is there a way to reconcile this and generate information to make new drugs?
Diazepam CGS-9896
12
•Describes the optimal binding of a protein to a ligand.
•Shows how different structures bind to same site.