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Printable Handouts
Navigable Slide Index
- Introduction
- Content
- HTS vs. fragment approaches
- Two and three letter words
- Word principles apply to molecules
- “Chemical space” is unimaginably large
- Lower number of smaller fragments
- Fragment-based lead discovery
- Historical development
- Why did this take so long?
- Why not just screen at high concentrations?
- Example reactive moieties
- PAINs (Pan Assay INterference Compounds)
- Many compounds form visualized aggregates
- How much of a problem is aggregation?
- Protecting yourself from aggregators
- But remain vigilant! case study with cruzain
- So how do you find low-affinity fragments?
- Finding fragments today
- X-ray crystallography
- NMR – protein detected
- NMR – ligand detected
- Surface plasmon resonance (SPR)
- Functional screening
- Computational screening
- Thermal shift
- Other methods
- What methods are people using?
- Evaluating a fragment
- What is a fragment?
- How large can fragments be?
- LE: binding energy per non-hydrogen atom
- LE: how efficient do you need to be?
- Other ways to evaluate fragments
- What metrics are being used?
- What can you do with a fragment?
- Hsp90 clinical compound from Astex
- Mutant B-Raf inhibitor from Plexxikon/Roche
- Fragments do not always overlap
- Linking fragments (1)
- Linking fragments (2)
- How much is fragment linking worth?
- Superadditivity from extremely weak fragments
- The trouble with linking
- Fragment linking for LDHA
- Fragment linking: Abbott’s Bcl-xL inhibitors
- Tethering with extenders on PDK1
- Who’s working with fragments?
- Fragment-derived molecules in the clinic
- Resources – books
- Resources – web
Topics Covered
- Advantages of fragment-based approaches
- Problems and pitfalls
- Methods to find fragments
- Evaluating fragments
- Fragment growing
- Fragment linking
- Summary and resources
Talk Citation
Erlanson, D.A. (2013, September 23). Fragment-based lead discovery [Video file]. In The Biomedical & Life Sciences Collection, Henry Stewart Talks. Retrieved November 21, 2024, from https://doi.org/10.69645/KMVB2713.Export Citation (RIS)
Publication History
Financial Disclosures
- Dr. Daniel A. Erlanson, Stock Shareholder (Self-managed): Carmot Therapeutics, Inc. (founder and President).
A selection of talks on Methods
Transcript
Please wait while the transcript is being prepared...
0:00
Today I'm going
to tell you about an approach
to drug discovery called
fragment-based lead discovery,
which has really started
coming to preeminence
in the past decade or so.
0:11
My presentation is in three parts.
The first is an
introduction to the concept
of fragment-based lead discovery
as well as some of the problems
that can arise.
And then I'm going to tell you
about methods to find, as well
as evaluate fragments, and close
by giving you a few examples
of how this has been
successfully applied
as well as for other resources.
0:34
A prior talk in the
series was devoted
to high throughput screening.
And you can think about
high throughput screening
as trying to guess a word by
making all possible combinations
of letters.
And if you screen through
enough word combinations,
you'll eventually be able
to discover your ligand.
In the case of
fragment-based approaches,
rather than trying to explore all
possible combinations of say, six
letters, you would look for
individual word fragments,
for example, a LIG and
an AND, and then link
those together to find your ligand.
Or, more commonly, you might find
a single-word fragment, say a LIG,
and then grow that letter by
letter into your final ligand.
1:23
To understand why this
process is more efficient,
it helps to think of Scrabble.
Those of you who
are serious players
will know that there are
exactly 96 two-letter words
that are permissible.
However, if you add one letter,
the number of possibilities
increases by more than
an order of magnitude.