Small Molecule Enzyme Inhibitors Research Articles

Indoleamine 2,3-Dioxygenase and Its Therapeutic Inhibition in Cancer.

The tryptophan catabolic enzyme indoleamine 2,3-dioxygenase-1 (IDO1) has attracted enormous attention in driving cancer immunosuppression, neovascularization, and metastasis. IDO1 suppresses local CD8+ T effector cells and natural killer cells and induces CD4+ T regulatory cells (iTreg) and myeloid-derived suppressor cells (MDSC). The structurally distinct enzyme tryptophan dioxygenase (TDO) also has been implicated recently in immune escape and metastatic progression. Lastly, emerging evidence suggests that the IDO1-related enzyme IDO2 may support IDO1-mediated iTreg and contribute to B-cell inflammed states in certain cancers. IDO1 and TDO are upregulated widely in neoplastic cells but also variably in stromal, endothelial, and innate immune cells of the tumor microenviroment and in tumor-draining lymph nodes. Pharmacological and genetic proofs in preclinical models of cancer have validated IDO1 as a cancer therapeutic target. IDO1 inhibitors have limited activity on their own but greatly enhance "immunogenic" chemotherapy or immune checkpoint drugs. IDO/TDO function is rooted in inflammatory programming, thereby influencing tumor neovascularization, MDSC generation, and metastasis beyond effects on adaptive immune tolerance. Discovery and development of two small molecule enzyme inhibitors of IDO1 have advanced furthest to date in Phase II/III human trials (epacadostat and navoximod, respectively). Indoximod, a tryptophan mimetic compound with a different mechanism of action in the IDO pathway has also advanced in multiple Phase II trials. Second generation combined IDO/TDO inhibitors may broaden impact in cancer treatment, for example, in addressing IDO1 bypass (inherent resistance) or acquired resistance to IDO1 inhibitors. This review surveys knowledge about IDO1 function and how IDO1 inhibitors reprogram inflammation to heighten therapeutic responses in cancer.

Genombasierte Suche nach Protease-Inhibitoren aus bakteriellen Quellen

Bacteria are a rich source for small-molecule inhibitors of proteases and protease-like enzymes with various therapeutic applications. These molecules often comprise distinct structural moieties, so called warheads which mediate specific interactions with the target enzymes. Knowledge on the biosynthesis of the protease inhibitors warheads can be used to search for orphan pathways with similar capacities in bacterial genomes. The identified biosynthetic gene clusters likely encode the production of new protease inhibitors with the same mode of action as the template compound.

DNA-linked Inhibitor Antibody Assay (DIANA) for sensitive and selective enzyme detection and inhibitor screening.

Human diseases are often diagnosed by determining levels of relevant enzymes and treated by enzyme inhibitors. We describe an assay suitable for both ultrasensitive enzyme quantification and quantitative inhibitor screening with unpurified enzymes. In the DNA-linked Inhibitor ANtibody Assay (DIANA), the target enzyme is captured by an immobilized antibody, probed with a small-molecule inhibitor attached to a reporter DNA and detected by quantitative PCR. We validate the approach using the putative cancer markers prostate-specific membrane antigen and carbonic anhydrase IX. We show that DIANA has a linear range of up to six logs and it selectively detects zeptomoles of targets in complex biological samples. DIANA's wide dynamic range permits determination of target enzyme inhibition constants using a single inhibitor concentration. DIANA also enables quantitative screening of small-molecule enzyme inhibitors using microliters of human blood serum containing picograms of target enzyme. DIANA's performance characteristics make it a superior tool for disease detection and drug discovery.

Abstract 2971: Optides (optimized knottin peptides) computationally designed to target the oncogenic HIPPO pathway

Abstract The HIPPO pathway plays a critical role in contact inhibition, a pathway that is commonly dysregulated in many human cancers (including liver, colon, ovarian, and lung) and which relies on the intranuclear interaction of the transcriptional coactivator YAP and the transcription factor TEAD(1-4). This pathway also plays a crucial role in recovery from injury; for example, its regulated repression allows hepatocytes to divide and replace tissue lost to a partial hepatectomy, after which its activation suppresses cell growth and prevents tissue overgrowth. While small molecule enzyme inhibitors have proven to be a revelation in cancer therapy, cell growth signaling via protein-protein interactions has proven much more difficult to drug. While Antibodies can be effective in targeting extracellular or cell surface epitopes, intracellular targets, such as the interaction between YAP and TEAD, are not amenable to antibody-based therapeutics. Optides are small disulfide-knotted peptides (knottins) and serve to bridge these capabilities; they are large enough to interfere with protein-protein interactions, but small enough to penetrate into the cytosol. Examples include imperatoxin, an activator of mitochondrial ryanodine receptors, and Tumor Paint, which contains an optimized variant of chlorotoxin conjugated to a fluorescent probe and is capable of accumulating in a wide range of tumor types. To test whether Optides can abrogate oncogenic signaling mediated by protein-protein interactions, we created libraries of computationally designed candidates to target the TEAD/YAP interface. The library is expressed on the surface of mammalian cells, chosen for the improved fidelity of disulfide bridge connectivity observed in the mammalian secretory pathway as compared to that found in yeast. By repetitive screening against soluble TEAD protein, we are optimizing the pool of candidates for targeting TEAD. The lead Optides will be characterized for their ability to reduce YAP-TEAD interaction, and to impair YAP-mediated cell growth. Owing to the wide variety of knottin scaffolds, both natural and in silico designed, this flexible technology could be applied to other targets in order to impair oncogenic protein-protein interactions. Citation Format: Zachary R. Crook, Philip Bradley, Chris King, Andrew J. Mhyre, David Baker, James M. Olson. Optides (optimized knottin peptides) computationally designed to target the oncogenic HIPPO pathway. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2971.

Effective Quenchers Are Required to Eliminate the Interference of Substrate: Cofactor Binding in the HAT Scintillation Proximity Assay.

Histone acetyltransferases (HATs) mediate the transfer of an acetyl group from the cofactor, acetyl-CoA, to the side chain amino group of specific lysines in diverse protein substrates, most notably nuclear histones. The deregulation of HATs is connected to a number of disease states. Reliable and rapid biochemical assays for HATs are critical for understanding biological functions of protein acetylation, as well as for screening small-molecule inhibitors of HAT enzymes. In this report, we present a scintillation proximity assay (SPA) for the measurement of HAT enzymatic activities. The acetyl donor was [(3)H]Ac-CoA, and a biotin-modified histone peptide served as the HAT substrate. After the HAT reaction, streptavidin-coated beads were added to induce proximity of acetylated substrate to the scintillant molecules. However, we observed strong nonspecific binding between the cofactor and the histone peptide substrates, which adversely complicated the SPA performance. To prevent this problem, a set of chemical agents were evaluated to eliminate the cofactor-substrate interaction, thus providing reliable SPA readings. With optimization, the SPA showed consistent and robust performance for HAT activity measurement and HAT inhibitor evaluation. Overall, this mix-and-measure assay does not require any washing procedure, can be utilized in the microplate format, and is well suited for high-throughput screening of HAT chemical modulators.

Acyl-coenzyme A:cholesterol acyltransferase 1 blockage enhances autophagy in the neurons of triple transgenic Alzheimer's disease mouse and reduces human P301L-tau content at the presymptomatic stage

Patients with Alzheimer's disease (AD) display amyloidopathy and tauopathy. In mouse models of AD, pharmacological inhibition using small molecule enzyme inhibitors or genetic inactivation of acyl-coenzyme A (Acyl-CoA):cholesterol acyltransferase 1 (ACAT1) diminished amyloidopathy and restored cognitive deficits. In microglia, ACAT1 blockage increases autophagosome formation and stimulates amyloid β peptide1-42 degradation. Here, we hypothesize that in neurons ACAT1 blockage augments autophagy and increases autophagy-mediated degradation of P301L-tau protein. We tested this possibility in murine neuroblastoma cells ectopically expressing human tau and in primary neurons isolated from triple transgenic AD mice that express mutant forms of amyloid precursor protein, presenilin-1, and human tau. The results show that ACAT1 blockage increases autophagosome formation and decreases P301L-tau protein content without affecting endogenous mouse tau protein content. In vivo, lacking Acat1 decreases P301L-tau protein content in the brains of young triple transgenic AD mice but not in those of old mice, where extensive hyperphosphorylations and aggregation of P301L-tau take place. These results suggest that, in addition to ameliorating amyloidopathy in both young and old AD mice, ACAT1 blockage may benefit AD by reducing tauopathy at early stage.

EnPlex, a high throughput flow cytometry platform to assess potency and selectivity of small molecule enzyme inhibitors

EnPlex, a high throughput flow cytometry platform to assess potency and selectivity of small molecule enzyme inhibitors

HCV-targeted Antivirals: Current Status and Future Challenges

Hepatitis C virus (HCV) is the major etiological agent of human non-A and non-B hepatitis, affecting more than 170 million people worldwide. While the current standard of care for the treatment of HCV infection is ribavirin in combination with interferon-α (IFN-α), this therapeutic regimen presents several drawbacks, mainly related to important and serious side effects, to resistance issues, and to the lack of efficacy for the treatment of specific viral genotypes. In 2011, the FDA approved two HCV-targeted antivirals, namely boceprevir and telaprevir. These two drugs inhibit the protease activity of the viral enzyme NS3/4A, and in Phase III clinical trials proved to be effective in achieving sustained virological response rate up to 75%. However, problems associated with these therapeutic regimens still exist and need to be addressed. Intense research efforts in the field are aimed at discovering small-molecule inhibitors of HCV enzymes and proteins such as NS5B and NS5A and at developing NS3 protease inhibitors active against resistant viruses expressing mutated NS3 protease. The most recent advances for the rational drug design of such inhibitors are here reviewed.

Biochemical characterization of prostate-specific membrane antigen from canine prostate carcinoma cells

Prostate-specific membrane antigen (PSMA) remains an important target for diagnostic and therapeutic application for human prostate cancer. Model cell lines have been recently developed to study canine prostate cancer but their PSMA expression and enzymatic activity have not been elucidated. The present study was focused on determining PSMA expression in these model canine cell lines and the use of fluorescent small-molecule enzyme inhibitors to detect canine PSMA expression by flow cytometry. Western blot and RT-PCR were used to determine the transcriptional and translational expression of PSMA on the canine cell lines Leo and Ace-1. An endpoint HPLC-based assay was used to monitor the enzymatic activity of canine PSMA and the potency of enzyme inhibitors. Flow cytometry was used to detect the PSMA expressed on Leo and Ace-1 cells using a fluorescently tagged PSMA enzyme inhibitor. Canine PSMA expression on the Leo cell line was confirmed by Western blot and RT-PCR, the enzyme activity, and flow cytometry. Kinetic parameters Km and Vmax of PSMA enzymatic activity for the synthetic substrate (PABGγG) were determined to be 393 nM and 220 pmol min(-1) mg protein(-1) , respectively. The inhibitor core 1 and fluorescent inhibitor 2 were found to be potent reversible inhibitors (IC50 = 13.2 and 1.6 nM, respectively) of PSMA expressed on the Leo cell line. Fluorescent labeling of Leo cells demonstrated that the fluorescent PSMA inhibitor 2 can be used for the detection of PSMA-positive canine prostate tumor cells. Expression of PSMA on Ace-1 was low and not detectable by flow cytometry. The results described herein have demonstrated that PSMA is expressed on canine prostate tumor cells and exhibits similar enzymatic characteristics as human PSMA. The findings show that the small molecule enzyme inhibitors currently being studied for use in diagnosis and therapy of human prostate cancer can also be extended to include canine prostate cancer. Importantly, the findings demonstrate that the potential of the inhibitors for use in diagnosis and therapy can be evaluated in an immunocompetent animal model that naturally develops prostate cancer before use in humans.

Targeting glucose metabolism in patients with cancer

Nearly a century ago, Otto Warburg made the astute observation that the metabolic properties of cancer cells differ markedly from those of normal cells. Several decades passed before the concept of exploiting cancer cell metabolism came into clinical practice with the advent of chemotherapy, the underlying principle of which is to target rapidly dividing cells by interfering with critical processes that are all, on some level, driven by cell metabolism. Although chemotherapy can be quite effective, success rates are highly variable and the adverse effects associated with treatment often outweigh the benefits due to the fact that chemotherapy is indiscriminately cytotoxic against all rapidly dividing cells, cancerous or healthy. During the past several years, a more intricate understanding of cancer cell metabolism has permitted the development of targeted therapies that aim to specifically target cancer cells and spare healthy tissue by exploiting the altered metabolism of cancer cells. The identification of new metabolic targets and the subsequent development of small-molecule inhibitors of metabolic enzymes have demonstrated the utility and promise of targeting cancer cell metabolism as an anticancer strategy. This review summarizes recent advances in the identification and characterization of several metabolic enzymes as emerging anticancer targets.

Future Frontiers in Small Molecule Inhibitors of Protein-Protein Interactions

Protein-protein interactions (PPIs) are ubiquitous in essential biological processes such as cell proliferation and differentiation, host-pathogen interactions, and signal transduction pathways [1]. Pioneering advances in the field of interactomics have uncovered new net-works of protein interactions within cells, with esti-mates for the size of the interactome ranging up to 650,000 PPIs [2]. However, targeting PPIs has histori-cally been considered to be a particularly challenging task due to their typically large size (>1,500 A) and amorphous nature that lack well-defined crevices for recognition by small molecules. Not surprisingly, the pharmaceutical landscape over the last century has been dominated by programs for small molecule in-hibitors of enzymes (particularly kinases), G-protein-coupled receptors, protein transporters and ion chan-nels that account for the majority of known drugs.

Developing inhibitors of glycan processing enzymes as tools for enabling glycobiology

Glycoconjugates are ubiquitous biomolecules found in all kingdoms of life. These diverse structures are metabolically responsive and occur in a cell line- and protein-specific manner, conferring tissue type-specific properties. Glycans have essential roles in diverse processes, including, for example, intercellular signaling, inflammation, protein quality control, glucohomeostasis and cellular adhesion as well as cell differentiation and proliferation. Many mysteries remain in the field, however, and uncovering the physiological roles of various glycans remains a key pursuit. Realizing this aim necessitates the ability to subtly and selectively manipulate the series of different glycoconjugates both in cells and in vivo. Selective small-molecule inhibitors of glycan processing enzymes hold great potential for such manipulation as well as for determining the function of 'orphan' carbohydrate-processing enzymes. In this review, we discuss recent advances and existing inhibitors, the prospects for small-molecule inhibitors and the challenges associated with generating high-quality chemical probes for these families of enzymes. The coordinated efforts of chemists, biochemists and biologists will be crucial for creating and characterizing inhibitors that are useful tools both for advancing a basic understanding of glycobiology in mammals as well as for validating new potential therapeutic targets within this burgeoning field.

Current Limitations And Future Opportunities For Epigenetic Therapies

This article reviews progress in epigenetic therapies that hope to improve the treatment of cancer. Tumors show widespread, aberrant epigenetic changes, leading to changes in the expression of genes involved in all the hallmarks of cancer. These epigenetic changes can potentially be reversed using small-molecule inhibitors of enzymes involved in maintenance of the epigenetic state. DNA-demethylating agents and histone deacetylase inhibitors have shown anti-tumor activity against certain hematological malignancies; however, their activity in solid tumors remains more uncertain. Major challenges remain in delivery of epigenetic therapy, maintenance of a pharmacodynamic response and achievement of a therapeutic index. We believe histone lysine methyl transferases are a highly promising epigenetic target, which has yet to be clinically exploited. Crystallographic studies on histone lysine methyl transferases provide insights into their mechanism and specificity crucial for the design and development of small-molecule inhibitors.

Targeting the Kynurenine Pathway-Related Alterations in Alzheimer's Disease: A Future Therapeutic Strategy

Alzheimer's disease (AD) is a chronic neurodegenerative disorder associated with dementia as a main feature. Despite decades of thorough research in the field of AD, the pathomechanism is still not fully understood. The development of novel experimental models can help us in the discovery of both genetic and non-genetic components of disease pathogenesis. As currently available therapies in AD can provide merely moderate or only temporary symptomatic relief, there is a great demand for the development of new drugs with higher therapeutic potential. Some of the candidates would be those targeting the kynurenine pathway, the neuroactive metabolites of which are surely involved in both neurodegeneration and neuroprotection, mainly in relation with glutamate excitotoxicity and oxidative stress. Both analogs of the neuroprotective kynurenic acid and small molecule enzyme inhibitors preventing the formation of neurotoxic compounds may have potential therapeutic significance. However, there is a great need for new strategies to improve efficacy, transport across the blood-brain barrier and bioavailability, naturally with simultaneous minimization of the adverse side-effects.

Abstract LB-258: Small-molecule inhibitors of de-ubiquitinating enzymes for cervical cancer treatment

Abstract Title. Small-Molecule Inhibitors of de-Ubiquitinating Enzymes for Cervical Cancer Treatment Abstract: Human Papillomavirus (HPV) is the primary cause of cervical cancer and responsible for 5% of all cancers worldwide. While HPV vaccines can be an effective preventive measure against cervical cancer, there are currently no virus-specific therapies for it, and the efficacy of standard surgical and chemo/radiotherapies is limited for advanced disease. The E6 oncoprotein of HPV exerts its oncogenic activity by binding to the E3 ubiquitin ligase E6-AP and redirects its activity towards p53 and other tumor suppressor proteins for rapid ubiquitin-mediated proteasomal degradation. Therefore, stabilization of p53 via preventing its ubiquitin-mediated degradation represents a valid therapeutic approach for cervical cancer treatment. De-ubiquitinating enzymes are an attractive novel “druggable” target for cervical cancer as they are responsible for controlling the steady state levels of proteins (i.e. p53 and E6-AP) crucial for maintaining the transformed status of cervical cancer cells, upstream proteasome. Thus, their inhibition is potentially associated with less toxic effects as compared to inhibition of proteasomes. During a structure-based screening of chalcone-based small-molecule inhibitors of ubiquitin-mediated protein degradation we have recently identified a novel class of molecules capable of inhibiting the ubiquitin-mediated protein degradation upstream proteasomes. The lead compound of the series, contains the α-β unsaturated carbonyl system, as the molecular determinant for inhibiting de-ubiquitinating enzyme activities and: i) is capable of inducing acute perturbation of the ubiquitin-mediated protein degradation pathways accompanied by accumulation of poly-ubiquitinated species and reduction of mono-, di-, and tri-ubiquitin species, ii) has no effect on the catalytic activities of purified proteasomes or proteasome in living cells, iii) is capable of induce aggresome formation, iv) is capable of rescuing p53 levels/functions in cervical cancer cells which are accompanied by decrease in the levels of Cyclin D1 and failure for the cells to enter the S-phase of the cell cycle, v) is capable of preventing tumor-colony formation and induces onset of apoptosis via caspase-3 activation in cervical cancer cells without affecting the viability of normal cells. Therefore, we believe in the feasibility of using our lead compound in preclinical model of cervical cancer to test its efficacy as antineoplastic agent. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-258. doi:10.1158/1538-7445.AM2011-LB-258

New Trend of Antithrombotic Therapy

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with important morbidity and mortality. AF increases the risk of stroke by a factor of five. Advances in antithrombotic therapy began when traditional anticoagulant agents such as heparin and the vitamin K antagonists (VKAs) like warfarin became commercially available in the 1940s and 1950s. VKAs have well documented limitations, including a delayed onset of action and a poor pharmacokinetic profile, large interindividual dosing differences, a narrow therapeutic index, interactions with dietary vitamin K and a large number of other medications, and the need for constant patient education, patient compliance and frequent follow-up. These limitations make the use of VKAs complex in the clinical setting, creating a burden for patients and healthcare providers. Recent investigation was focused on the identification of small-molecule inhibitors of coagulation enzymes as novel strategy. Two hot targets are the two key serine proteases in the coagulation cascade: thrombin (activated factor IIa), and activated factor X (FXa). The 3 orally active agents in the market are dabigatran (direct thrombin inhibitor, DTI), rivaroxaban (Xa inhibitor), and apixaban (Xa inhibitor). All of them have been shown to be effective in large-scale clinical trials, including RE-LY, ROCKET AF, and AVERROES. It is very clear that we are facing a completely new era of anti-thrombotic therapy in AF.

Seeking the causes and solutions to imatinib-resistance in chronic myeloid leukemia

Although only 5000 new cases of chronic myeloid leukemia (CML) were seen in the United States in 2009, this neoplasm continues to make scientific headlines year-after-year. Advances in understanding the molecular pathogenesis coupled with exciting developments in both drug design and development, targeting the initiating tyrosine kinase, have kept CML in the scientific limelight for more than a decade. Indeed, imatinib, a small-molecule inhibitor of the leukemia-initiating Bcr-Abl tyrosine kinase, has quickly become the therapeutic standard for newly diagnosed chronic phase-CML (CP-CML) patients. Yet, nearly one-third of patients will still have an inferior response to imatinib, either failing to respond to primary therapy or demonstrating progression after an initial response. Significant efforts geared toward understanding the molecular mechanisms of imatinib resistance have yielded valuable insights into the cellular biology of drug trafficking, enzyme structure and function, and the rational design of novel small molecule enzyme inhibitors. Indeed, new classes of kinase inhibitors have recently been investigated in imatinib-resistant CML. Understanding the pathogenesis of tyrosine kinase inhibitor resistance and the molecular rationale for the development of second and now third generation therapies for patients with CML will be keys to further disease control over the next 10 years.

Histone deacetylase (HDAC) inhibitors in recent clinical trials for cancer therapy.

Heritable changes in gene expression that are not based upon alterations in the DNA sequence are defined as epigenetics. The most common mechanisms of epigenetic regulation are the methylation of CpG islands within the DNA and the modification of amino acids in the N-terminal histone tails. In the last years, it became evident that the onset of cancer and its progression may not occur only due to genetic mutations but also because of changes in the patterns of epigenetic modifications. In contrast to genetic mutations, which are almost impossible to reverse, epigenetic changes are potentially reversible. This implies that they are amenable to pharmacological interventions. Therefore, a lot of work in recent years has focussed on the development of small molecule enzyme inhibitors like DNA-methyltransferase inhibitors or inhibitors of histone-modifying enzymes. These may reverse misregulated epigenetic states and be implemented in the treatment of cancer or other diseases, e.g., neurological disorders. Today, several epigenetic drugs are already approved by the FDA and the EMEA for cancer treatment and around ten histone deacetylase (HDAC) inhibitors are in clinical development. This review will give an update on recent clinical trials of the HDAC inhibitors used systemically that were reported in 2009 and 2010 and will present an overview of different biomarkers to monitor the biological effects.

Metal Cofactors in the Structure and Activity of the Fowlpox Resolvase

Poxvirus DNA replication generates linear concatemers containing many copies of the viral genome with inverted repeat sequences at the junctions between monomers. The inverted repeats refold to generate Holliday junctions, which are cleaved by the virus-encoded resolvase enzyme to form unit-length genomes. Here we report studies of the influence of metal cofactors on the activity and structure of the resolvase of fowlpox virus, which provides a tractable model for in vitro studies. Small-molecule inhibitors of related enzymes bind simultaneously to metal cofactors and nearby surface amino acid residues, so understanding enzyme–cofactor interactions is important for the design of antiviral agents. Analysis of inferred active-site residues (D7, E60, K102, D132, and D135) by mutagenesis and metal rescue experiments specified residues that contribute to binding metal ions and that multiple binding sites are probably involved. Differential electrophoretic analysis was used to map the conformation of the DNA junction when bound by resolvase. For the wild-type complex in the presence of EDTA (ethylenediaminetetraacetic acid) or Ca2+, migration was consistent with the DNA arms arranged in near-tetrahedral geometry. However, the D7N active-site mutant resolvase held the arms in a more planar arrangement in EDTA, Ca2+, or Mg2+ conditions, implicating metal-dependent contacts at the active site in the larger architecture of the complex. These data show how divalent metals dictate the conformation of FPV resolvase–DNA complexes and subsequent DNA cleavage.

Chemical Biology Meets Biological Chemistry Minireview Series

Abstract What's the difference between and biology? One of us (JMG) received his Ph.D. at an institution where the biochemistry building was called the Laboratory of Biology, but that was a long time ago and things have changed. Biological chemistry (or biochemistry), that is the study of life processes at the molecular level, is now quite distinct from chemical biology. According to Wikipedia, Chemical is a scientific discipline spanning the fields of chemistry and that involves the application of chemical techniques and tools, often compounds produced through synthetic chemistry, to the study and manipulation of biological systems. Throughout the 105-year history of the Journal of Biological Chemistry, papers using techniques of chemistry to understand biological processes have appeared in the Journal, and in fact, many papers describing the development of chemical reagents and small molecule enzyme inhibitors top the all-time most-cited list of JBC papers (see http://www.jbc.org/reports/most-cited). However, several new journals have now emerged to emphasize the growing importance of biology as a unique discipline, albeit within the bounds of biological The following minireviews emphasize the importance of uniting synthetic chemistry with biochemistry toward understanding complex biological processes; in other words, how relevant biology is to chemistry. These reviews highlight both the application of chemical techniques toward understanding life processes at the molecular level (i.e., biochemistry) and the development of synthetic compounds either as tools for research or as candidate therapeutics for human diseases. These topics are naturally within the scope of interest of the JBC.