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Published byAmelia Sparks Modified over 8 years ago
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Jump to first page Relational Data
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Jump to first page Inductive Logic Programming (ILP) n Can use ILP to find a set of rules capturing a property that the positive graphs have in common that no negative graph has. n This property is a kind of disjunction of subgraphs, where we allow one node in the graph to possibly play the role of multiple nodes in the subgraph.
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Jump to first page Rule
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Jump to first page Pharmacophores n A drug is a (typically) small organic molecule capable of binding to a target protein. n Binding depends on shape and on locations of charged groups, hydrophobic groups, etc. n If exact structure of target site is known, drug design is relatively easy -- but this is rarely known.
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Jump to first page Example of Binding
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Jump to first page Typical Practice n Test many molecules (1,000,000) to find some that bind to target (ligands). n Infer (induce) shape of target site from 3D structural similarities. n Shared 3D substructure is called a pharmacophore. n Perfect example of a machine learning task with spatial target.
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Pharmacophore expressed in English A Molecule M is active against Pseudomonas Aeruginosa if it has a conformation B such that: M has a hydrophobic group C, M has a hydrogen acceptor D, the distance between C and D in conformation B is 11.7 Angstroms M has a positively-charged atom E, the distance between C and E in conformation B is 4 Angstroms the distance between D and E in conformation B is 9.4 Angstroms M has a positively-charged atom F, the distance between C and F in conformation B is 11.1 Angstroms the distance between D and F in conformation B is 12.6 Angstroms the distance between E and F in conformation B is 8.7 Angstroms Tolerance 1.5 Angstroms
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Jump to first page Obvious Question 1 n Why don’t we just use one of the ligands (hits) as the drug? n Typically they don’t meet all the other requirements for drugs: u Non-toxic (other side effects) u Active enough (drink 2 gallons) u Metabolism (lasts long enough but not too long in the body) u Take by mouth? (gut-bloodstream)
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Jump to first page Obvious Question 2 n Why doesn’t a chemist just look at the ligands and figure out what they have in common? n Each molecule has many different shapes (conformers), any one of which might be the active one. Multiple instance problem (Dietterich, Lathrop, Lozano-Perez) n May be many molecules.
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Jump to first page The Logical Representation of a Pharmacophore
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Jump to first page ACE Pharmacophore n Molecule A is an ACE inhibitor if: n molecule A contains a zinc-site B, n molecule A contains a hydrogen acceptor C, n the distance between B and C is 7.89 +/- 0.75 A, n molecule A contains a hydrogen acceptor D, n the distance between B and D is 8.48 +/- 0.75 A, n the distance between C and D is 2.13 +/- 0.75 A, n molecule A contains a hydrogen acceptor E, n the distance between B and E is 4.89 +/- 0.75 A, n the distance between C and E is 3.11 +/- 0.75 A, n the distance between D and E is 3.75 +/- 0.75 A.
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Jump to first page Molecule 1
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Protein Function Gene Sequence Structural Motifs Chromosomal Location Gene/Protein LevelInteractions Gene Expression Protein Interactions FUNCTION
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