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Background: Cyclin-dependent kinases (CDKs) comprise an important protein family for development of drugs, mostly aimed for use in treatment of cancer but there is also potential for development of drugs for neurodegenerative diseases and diabetes. Since the early 1990s, structural studies have been carried out on CDKs, in order to determine the structural basis for inhibition of this protein target., Objective: Our goal here is to review recent structural studies focused on CDKs. We concentrate on latest developments in the understanding of the structural basis for inhibition of CDKs, relating structures and ligand-binding information., Method: Protein crystallography has been successfully applied to elucidate over 400 CDK structures. Most of these structures are complexed with inhibitors. We use this richness of structural information to describe the major structural features determining the inhibition of this enzyme., Results: Structures of CDK1, 2, 4-9, 12 13, and 16 have been elucidated. Analysis of these structures in complex with a wide range of different competitive inhibitors, strongly indicate some common features that can be used to guide the development of CDK inhibitors, such as a pattern of hydrogen bonding and the presence of halogen atoms in the ligand structure., Conclusion: Nowadays we have structural information for hundreds of CDKs. Combining the structural and functional information we may say that a pattern of intermolecular hydrogen bonds is of pivotal importance for inhibitor specificity. In addition, machine learning techniques have shown improvements in predicting binding affinity for CDKs., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Sequencing of parasite genomes opened the possibility to identify potential protein targets for drug development. Several protein targets have been found in the genome of Plasmodium falciparum, Trypanosoma cruzi, Trypanosoma brucei and Leishmania major. Bioinformatics analysis is an important tool for the identification of protein targets for drug development against parasitic diseases. In this review we comment about three protein targets, identified in parasite genomes, and discuss the main features that may guide future efforts for virtual screening initiatives.

Drug development has become the Holy Grail of many structural bioinformatics groups. The explosion of information about protein structures, ligand-binding affinity, parasite genome projects, and biological activity of millions of molecules opened the possibility to correlate this scattered information in order to generate reliable computational models to predict the likelihood of being able to modulate a target with a small-molecule drug. Computational methods have shown their potential in drug discovery and development allied with in vitro and in vivo methodologies. The present review discusses the main bioinformatics tools available for drug discovery and development.

Recent developments in computer power and chemoinformatics methodology make possible that a huge amount of data become available through internet. These databases are devoted to a wide spectrum of scientific fields. Here we are concerned with databases related to protein-drug interactions. More specifically, databases where potential new molecules could be accessed to be used in virtual screening initiatives. In the past decade several databases have been developed where molecules to be used in the virtual screening could be easily identified, downloaded and even purchased. This review describes and summarizes the recent advances in the development of these databases, and also the main applications related to virtual screening projects.

Parasitic protozoa infecting humans have a great impact on public health, especially in the developing countries. In many instances, the parasites have developed resistance against available chemotherapeutic agents, making the search for alternative drugs a priority. In line with the current interest in Protein Kinase (PK) inhibitors as potential drugs against a variety of diseases, the possibility that PKs may represent targets for novel anti-parasitic agents is being explored. Research into parasite PKs has benefited greatly from genome and EST sequencing projects, with the genomes from a few species fully sequenced (notably that from the malaria parasite Plasmodium falciparum) and several more under way, the structural features that are important to design specific inhibitors against these PKs will be reviewed in the present work.

EPSP synthase (EPSPS) is an essential enzyme in the shikimate pathway, transferring the enolpyruvyl group of phosphoenolpyruvate to shikimate-3-phosphate to form 5-enolpyruvyl-3-shikimate phosphate and inorganic phosphate. This enzyme is composed of two domains, which are formed by three copies of betaalphabetaalphabetabeta-folding units; in between there are two crossover chain segments hinging the nearly topologically symmetrical domains together and allowing conformational changes necessary for substrate conversion. The reaction is ordered with shikimate-3-phosphate binding first, followed by phosphoenolpyruvate, and then by the subsequent release of phosphate and EPSP. N-[phosphomethyl]glycine (glyphosate) is the commercial inhibitor of this enzyme. Apparently, the binding of shikimate-3-phosphate is necessary for glyphosate binding, since it induces the closure of the two domains to form the active site in the interdomain cleft. However, it is somehow controversial whether binding of shikimate-3-phosphate alone is enough to induce the complete conversion to the closed state. The phosphoenolpyruvate binding site seems to be located mainly on the C-terminal domain, while the binding site of shikimate-3-phosphate is located primarily in the N-terminal domain residues. However, recent results demonstrate that the active site of the enzyme undergoes structural changes upon inhibitor binding on a scale that cannot be predicted by conventional computational methods. Studies of molecular docking based on the interaction of known EPSPS structures with (R)- phosphonate TI analogue reveal that more experimental data on the structure and dynamics of various EPSPS-ligand complexes are needed to more effectively apply structure-based drug design of this enzyme in the future.

The increase in incidence of infectious diseases worldwide, particularly in developing countries, is worrying. Each year, 14 million people are killed by infectious diseases, mainly HIV/AIDS, respiratory infections, malaria and tuberculosis.. Despite the great burden in the poor countries, drug discovery to treat tropical diseases has come to a standstill. There is no interest by the pharmaceutical industry in drug development against the major diseases of the poor countries, since the financial return cannot be guaranteed. This has created an urgent need for new therapeutics to neglected diseases. A possible approach has been the exploitation of the inhibition of unique targets, vital to the pathogen such as the shikimate pathway enzymes, which are present in bacteria, fungi and apicomplexan parasites but are absent in mammals. The chorismate synthase (CS) catalyses the seventh step in this pathway, the conversion of 5-enolpyruvylshikimate-3-phosphate to chorismate. The strict requirement for a reduced flavin mononucleotide and the anti 1,4 elimination are both unusual aspects which make CS reaction unique among flavin-dependent enzymes, representing an important target for the chemotherapeutic agents development. In this review we present the main biochemical features of CS from bacterial and fungal sources and their difference from the apicomplexan CS. The CS mechanisms proposed are discussed and compared with structural data. The CS structures of some organisms are compared and their distinct features analyzed. Some known CS inhibitors are presented and the main characteristics are discussed. The structural and kinetics data reviewed here can be useful for the design of inhibitors.

Tuberculosis (TB) remains the leading cause of mortality due to a bacterial pathogen, Mycobacterium tuberculosis. However, no new classes of drugs for TB have been developed in the past 30 years. Therefore there is an urgent need to develop faster acting and effective new antitubercular agents, preferably belonging to new structural classes, to better combat TB, including MDR-TB, to shorten the duration of current treatment to improve patient compliance, and to provide effective treatment of latent tuberculosis infection. The enzymes in the shikimate pathway are potential targets for development of a new generation of antitubercular drugs. The shikimate pathway has been shown by disruption of aroK gene to be essential for the Mycobacterium tuberculosis. The shikimate kinase (SK) catalyses the phosphorylation of the 3-hydroxyl group of shikimic acid (shikimate) using ATP as a co-substrate. SK belongs to family of nucleoside monophosphate (NMP) kinases. The enzyme is an alpha/beta protein consisting of a central sheet of five parallel beta-strands flanked by alpha-helices. The shikimate kinases are composed of three domains: Core domain, Lid domain and Shikimate-binding domain. The Lid and Shikimate-binding domains are responsible for large conformational changes during catalysis. More recently, the precise interactions between SK and substrate have been elucidated, showing the binding of shikimate with three charged residues conserved among the SK sequences. The elucidation of interactions between MtSK and their substrates is crucial for the development of a new generation of drugs against tuberculosis through rational drug design.