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Evaluation of the effects of glycosaminoglycans on the activity of cysteine protease catatepsin inhibitors


Cathepsins B and L, cysteine lysosomal proteases, are important targets in the development of a variety of therapeutic agents due to the involvement of these proteases in various disease conditions. They are associated with cancer progression due to the degradation capacity of the extracellular matrix, facilitating invasion, angiogenesis and metastasis, in addition to favoring viral replication in human cells. Studies suggest that GAGs play a key role in cell signaling, which serves to modulate a large number of biochemical processes. Interaction between proteins and GAGs may favor protection against proteolytic degradation, modulation of biological activity, and in this sense studies have shown the activation of cysteine proteases modulated by GAGs. In addition, they accelerate the auto catalytic activation of cathepsins L and B and affect the activity and stability of mature cysteine cathepsins. The increase in the activity of cathepsins B and L has been observed in cases of breast and prostate cancers and early stages of gastric carcinoma, being considered as markers for these diseases and suggested as a prognosis for recurrences of these types of tumors. Therefore, inhibitors of these peptidases should be considered in advanced stages of cancer. In this sense, it is important to evaluate the behavior of inhibitors in an environment containing GAGs to identify possible interferences of these on the inhibitory process, since GAGs are capable of modulating the activity of cysteine cathepsins. Antithrombin-mediated inhibition of huPK (plasma kallikrein) was found to be increased by the action of heparan sulfate and derematan sulfate and impaired by chondroitin sulfate. Furthermore, inhibition of huPK by the C1 inhibitor showed a small increase in the presence of GAGs. i) GAGs could bind to enzymes inducing a conformational change, leading to a more or less active form; ii) GAGs can bind to natural substrates or inhibitors, neutralizing their positive charges and interfering with their hydrolysis or inhibition. In addition to this, the literature reports that GAGs may undergo conformational changes induced by coordination compounds such as platinum, and consequently modulation of the GAG's biological function. A platinum complex was able to inhibit the activity of GAGs by the formation of non-covalent interactions and thereby preventing the formation of the growth factor complex and the GAG heparan sulfate (HS) and consequently reduction of metastasis due to loss of HS function. Thus, our objective will be to evaluate the effects of sulfated and non-sulfated glycosaminoglycans on the inhibitory activity of calcogenoquinoline compounds and compounds derived from palladium on cysteine proteases cathepsins B and L through kinetic, physicochemical, cellular tests and molecular docking and molecular dynamics simulation in the absence and presence of sulfated GAGs and modified heparins, and structural evaluation of GAGs by the effect of coordination compounds derived from palladium by mono and two-dimensional NMR such as 1H, HSQC, TOCSY and NOESY. (AU)

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