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the biological society access to the experimental data <strong>in</strong> a constructive manner. Data <strong>in</strong>corporated <strong>in</strong> prote<strong>in</strong> structure<br />

databases often consists of three dimensional coord<strong>in</strong>ates as well as experimental details, such as unit cell dimensions and<br />

angles for x-ray crystallography resolved structures. S<strong>in</strong>ce PDB is the master prote<strong>in</strong> 3D structure database, therefore,<br />

before highlight<strong>in</strong>g some of the major prote<strong>in</strong> structure databases, a brief historical background on PDB is provided <strong>in</strong> the<br />

next section.<br />

2.1 Historical background of PDB<br />

In 1968, a small but <strong>in</strong>creas<strong>in</strong>g number of prote<strong>in</strong> structures determ<strong>in</strong>ed by X-ray diffraction, and the newly exist<strong>in</strong>g<br />

molecular graphics display, known as the Brookhaven RAster Display (BRAD), to visualize these prote<strong>in</strong> structures <strong>in</strong><br />

3D were the driv<strong>in</strong>g forces that led to the birth of the PDB. Later, with the support of Walter Hamilton a chemist at the<br />

Brookhaven National Laboratory, Edgar Meyer (Texas A&M University) began to write software to store atomic coord<strong>in</strong>ate<br />

files <strong>in</strong> a universal format to make them accessible for geometric and graphical assessment. By 1971, one of Meyer’s<br />

programs, SEARCH, facilitated researchers to distantly access <strong>in</strong>formation from the database to study prote<strong>in</strong> structures<br />

offl<strong>in</strong>e [11]. SEARCH was helpful <strong>in</strong> enabl<strong>in</strong>g network<strong>in</strong>g, thus mark<strong>in</strong>g the practical establishment of the PDB.<br />

Soon after the death of Hamilton’s <strong>in</strong> 1973, Tom Koetzle took over the direction of the PDB, and <strong>in</strong> 1974 the first PDB<br />

Newsletter was circulated to expla<strong>in</strong> the details of data deposition and remote access. At this <strong>in</strong>stant, only thirteen structures<br />

were prepared for distribution and four were pend<strong>in</strong>g. The PDB cont<strong>in</strong>ued <strong>in</strong> Brookhaven until 1998, and <strong>in</strong> 1999 the PDB<br />

was transferred to the Research Collaboratory for Structural Bio<strong>in</strong>formatics (RCSB) [12], under the directorship of Helen<br />

M. Berman of Rutgers University [13].<br />

In 2003, the Worldwide PDB (wwPDB) was formed which made PDB an <strong>in</strong>ternational organization, with RCSB PDB,<br />

the Macromolecular Structure Database at the European Bio<strong>in</strong>formatics Institute (MSD-EBI) and PDB Japan (PDBj) at the<br />

Institute for Prote<strong>in</strong> Research at Osaka University, Japan, act<strong>in</strong>g as the found<strong>in</strong>g members [14]. This laid the foundation for<br />

the PDB to rema<strong>in</strong> a universal worldwide resource of structural biology data [15].<br />

2.2 Prote<strong>in</strong> structure databases<br />

The structure databases are divided <strong>in</strong>to two subsections based on whether it consists of experimentally determ<strong>in</strong>ed<br />

structures or structure models. All these databases are listed <strong>in</strong> Table 1.<br />

S. No. Database L<strong>in</strong>k Description<br />

1. PDB http://www.rcsb.org/pdb/home/home.do X-ray & NMR data for biological macromolecules<br />

2. PDBsum http://www.ebi.ac.uk/pdbsum/ Pictorial representation of 3D structures<br />

3. CATH http://www.cathdb.<strong>in</strong>fo/ Prote<strong>in</strong> doma<strong>in</strong> structures<br />

4. SCOP http://scop.mrc-lmb.cam.ac.uk/scop/ Familial and structural prote<strong>in</strong> relationships<br />

5. MMDB http://www.ncbi.nlm.nih.gov/structure 3D structures that are l<strong>in</strong>ked to NCBI Entrez<br />

6. ModBase<br />

7. SWISS-MODEL Repository<br />

8.<br />

Database of Macromolecular<br />

Movements<br />

http://modbase.compbio.ucsf.edu/modbase-cgi/<br />

<strong>in</strong>dex.cgi<br />

http://swissmodel.expasy.org/<br />

repository/?pid=smr01&zid=async<br />

http://bio<strong>in</strong>fo.mbb.yale.edu/MolMovDB<br />

9. PROCARB http://procarb.org/<br />

Comparative prote<strong>in</strong> structure models<br />

Annotated 3D comparative prote<strong>in</strong> structure models<br />

Motions that occur <strong>in</strong> prote<strong>in</strong>s and other macromolecules<br />

3D structures of prote<strong>in</strong>-carbohydrate complexes &<br />

comparative models of glycoprote<strong>in</strong>s<br />

10. PMDB http://mi.caspur.it/PMDB/ 3D prote<strong>in</strong> models obta<strong>in</strong>ed by structure prediction methods.<br />

11. PDBTM http://pdbtm.enzim.hu/ Prote<strong>in</strong> Data Bank of Transmembrane Prote<strong>in</strong>s<br />

12. OPM http://opm.phar.umich.edu/<br />

2.2.1 Experimentally solved structure databases:<br />

2.2.1.1 Prote<strong>in</strong> Data Bank (PDB)<br />

Table 1: List of various important prote<strong>in</strong> structure and prote<strong>in</strong> model databases.<br />

OPM provides spatial arrangements of membrane prote<strong>in</strong>s<br />

with respect to the hydrocarbon core of the lipid bilayer.<br />

1. It is the chief source of structural data for biological macromolecules. PDB was founded at Brookhaven National<br />

Laboratories (BNL) [16] <strong>in</strong> 1971 as an archive for biological macromolecular crystal structures [17]. As of May 2013, there<br />

are 90206 biological macromolecular structures deposited <strong>in</strong> PDB [18]. The PDB database conta<strong>in</strong>s <strong>in</strong>formation regard<strong>in</strong>g<br />

experimentally-determ<strong>in</strong>ed structures of prote<strong>in</strong>s, nucleic acids, and complex assemblies. The data obta<strong>in</strong>ed by X-ray<br />

crystallography or NMR spectroscopy is deposited globally by biologists and biochemists which is freely accessible to the<br />

world wide community. Each PDB file conta<strong>in</strong>s xyz coord<strong>in</strong>ates of atoms and an entry <strong>in</strong> the PDB also <strong>in</strong>cludes <strong>in</strong>formation<br />

regard<strong>in</strong>g the <strong>chemistry</strong> of the macromolecule, the small-molecule ligands, various particulars of the data collection and<br />

structure ref<strong>in</strong>ement, and some structural descriptors. Altogether, a characteristic PDB entry has about 400 unique items of<br />

data. The PDB file format was formulated <strong>in</strong> 1976 and is very simple, human readable as well as used by countless computer<br />

applications [19].<br />

2.2.1.2 SCOP<br />

The prote<strong>in</strong>s <strong>in</strong> PDB have structural similarities with other prote<strong>in</strong>s and, may share a common evolutionary source.<br />

Therefore, the Structural Classification of Prote<strong>in</strong>s (SCOP) database [20] was created so that access to this <strong>in</strong>formation<br />

could be facilitated. Besides all the prote<strong>in</strong>s <strong>in</strong> the current version of PDB, it also <strong>in</strong>cludes many prote<strong>in</strong>s for which there are<br />

published descriptions but whose co-ord<strong>in</strong>ates do not exist yet. The classification <strong>in</strong> SCOP is based on hierarchical levels<br />

OMICS Group eBooks<br />

05

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