Perhaps if the ligand binding pocket were moved to a site where the conformation changes on cleavage are more pronounced, such as the region bounded by -sheet A and helix D, or the region bounded by -sheet A and helix F (Figure 6), the effects of S-to-R conformational change would have a significantly larger effect. prostate-specific serine Cevimeline hydrochloride protease, or thrombin, a key protease in the blood coagulation cascade. PSA is usually conspicuously overproduced in prostatic hyperplasia and is, therefore, a good way of targeting hyperplastic prostate tissues. Thrombin is usually released during clotting and consequently is ideal for conferring specificity to thrombotic sites. Using fluorescence-based titration assays, we also showed that CBG can be engineered to bind a new compound, thyroxine-6-carboxyfluorescein, instead of its physiological ligand, cortisol, thereby demonstrating that it is possible to tailor the hormone binding site to deliver a therapeutic drug. In addition, we proved that this efficiency with which CBG releases bound ligand can be increased by introducing some well-placed mutations. This proof-of-concept study has raised the prospect of a novel means of targeted drug delivery, using the serpin conformational change to combat the problem of off-target effects in the treatment of diseases. == Introduction == Since antiquity, Man has sought to use compounds extracted from plants to treat diseases such as cancer, often with little success. It was not until the interbellum years that the modern era of cancer chemotherapy really took hold, when toxic chemicals were found to be Rabbit Polyclonal to ZADH1 Cevimeline hydrochloride effective against this hitherto incurable disease. Nearly seventy years after the first real effective drug against cancer, nitrogen mustard (Bis(2-choroethyl)methylamine hydrochloride), was first introduced into clinical use[1], the vast majority of anti-cancer drugs are still highly toxic. These drugs need to kill tumour cells using overwhelming cytotoxicity while remaining innocuous to healthy tissue. Unfortunately, with little to differentiate between the two, it has frequently been found that the benefits in terms of overall survival are often marginal, while the risks of off-target toxicity, whether lethal or chronic, are high[2]. As a result, chemotherapy often causes a plethora of side-effects ranging from emesis, stomatitis and alopecia that reduce the patient’s quality of life, to leukopenia, febrile neutropenia and sepsis that are potentially debilitating[3],[4]. To reduce the incidence of these off-target toxicities, chemotherapeutic agents need to be targeted specifically to tumours. One of the earliest breakthroughs in attaining site-specificity in cancer therapy was the formulation of a styrene-maleic acid copolymer-conjugated neocarzinostatin (SMANCS), where the potent anti-tumour agent, neocarzinostatin, was attached to a lipophilic polymer, allowing it to penetrate more efficiently into solid tumours than intramuscular injection of the non-derivatised drug[5][7]. However, SMANCS and other similar polymer conjugates were found to be Cevimeline hydrochloride limited in their effectiveness in cases involving hypovascular tumours such as those seen in prostatic and pancreatic cancers[8]. Since then, a new class of antibody-based anti-cancer drugs has emerged. Some of these comprise antibodies conjugated to therapeutic drugs. The antibody recognises certain antigens specific to the tumour tissue, thus selectively directing the drug to the target. Naked’ antibodies have also been used to target tumour tissues directly for destruction by the body’s immune system. There are currently three antibody-drug conjugates and 11 naked monoclonal antibodies approved by the Food and Drug Administration for the treatment of cancers[9],[10]. Another form of immunotherapy that has gained traction in recent years is therapeutic vaccination. One such vaccine, Sipuleucel-T, has recently been approved for Cevimeline hydrochloride use on prostate cancer. This involves extracting the patient’s antigen-presenting cells and Cevimeline hydrochloride activating them in vitro with the tumour-associated antigen, prostate acid phosphatase, before injecting them back into the patient to prime a T cell response against the tumour[11],[12]. Despite numerous advances in the field, many of these new targeting methods are still not sufficiently specific to prevent off-target effects. Lipophilic conjugates were found to accumulate in neovasculature regardless of the tissue type[8], while many of the antibody conjugates and antibodies developed for cancer therapy target entire classes of proteins such as epithelial growth factor receptors (EGFRs) and kinases, which are found in.