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Cambridge MedChem Consulting

How Structural Biologists and the Protein Data Bank Contributed to Recent FDA New Drug Approvals

An interesting review DOI

Discovery and development of 210 new molecular entities (NMEs; new drugs) approved by the US Food and Drug Administration 2010–2016 was facilitated by 3D structural information generated by structural biologists worldwide and distributed on an open-access basis by the PDB. The molecular targets for 94% of these NMEs are known. The PDB archive contains 5,914 structures containing one of the known targets and/or a new drug, providing structural coverage for 88% of the recently approved NMEs across all therapeutic areas. More than half of the 5,914 structures were published and made available by the PDB at no charge, with no restrictions on usage >10 years before drug approval. Citation analyses revealed that these 5,914 PDB structures significantly affected the very large body of publicly funded research reported in publications on the NME targets that motivated biopharmaceutical company investment in discovery and development programs that produced the NMEs.

Macrocycles in the Protein Data Bank

The Protein Data Bank is an absolutely invaluable resource, the PDB is an archive of 3D structural information of proteins, nucleic acids, and bimolecular complex assemblies. However it is much, much more than a simple archive, the submitted structures are curated and annotated to add information about protein ID, sequence information, organism, ligand details etc. This allows users to interrogate the database in many different ways. The database currently holds 141209 entries, with over 10,000 new entries added every year. The vast majority are X-ray crystal structures but there are now over 12,000 NMR derived structures.

The PDB also contains 25626 chemical components - 24007 as free ligands in 106374 PDB file and you can search via a web interface or download the structures in sdf file format. However browsing through the downloaded file it was apparently that macrocycles were not well represented. A discussion with the extraordinarily helpful Rachel Kramer Green at PDB revealed the issue. Basically any ligand containing more that two amino-acids is treated as a protein not a ligand, there are other rules to deal with modified amino-acids etc. but the bottom line is that the only way to get a comprehensive view of macrocycles in the PDB is to download the entire PDB and programmatically by parsing the entire data set.

First we need to decide what size ring constitutes a macrocycle. asking the "internet" failed to produce a definitive answer.

macrocyclesize

You can read the results and download the script here.

pdbMacrocycles

There is also a page that discusses macrocycles in drug discovery.

There is also an upcoming meeting on Macrocycles, 3rd RSC BMCS Medicinal Chemistry Symposium on Macrocycles. Monday-Tuesday, 8th-9th October 2018, GlaxoSmithKline, Stevenage, UK. Full details are here http://www.maggichurchouseevents.co.uk/bmcs/Macrocycles-2018.htm. #BMCS_Macrocycles

The objective of this symposium is to promote scientific interaction between scientists with a shared interest in the field of Macrocycles. This area is responsible for a growing number of therapeutic approaches and development candidates, all of which go ‘beyond the rule-of–five’. As a researcher in this field, come along to hear about the latest advances and also to share in some of the secrets of discovering therapeutic agents which go beyond Lipinski’s rules.