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Diene rubbers are polymeric materials which present elastic properties and have double bonds in the macromolecular backbone after the polymerization process. Post-polymerization modifications of rubbers can be conducted by enzymatic or chemical methods. Enzymes are environmentally friendly catalysts and with the increasing demand for rubber waste management, biodegradation and biomodifications have become hot topics of research. Some rubbers are renewable materials and are a source of organic molecules, and biodegradation can be conducted to obtain either oligomers or monomers. On the other hand, chemical modifications of rubbers by click-chemistry are important strategies for the creation and combination of new materials. In a way to expand the scope of uses to other non-traditional applications, several and effective modifications can be conducted with diene rubbers. Two groups of efficient tools, enzymatic, and chemical modifications in diene rubbers, are summarized in this review. By analyzing stereochemical and reactivity aspects, the authors also point to some applications perspectives for biodegradation products and to rational modifications of diene rubbers by combining both methodologies.

The three-dimensional structure of tyrosinase has been crystallized from many species but not from Homo sapiens. Tyrosinase is a key enzyme in melanin biosynthesis, being an important target for melanoma and skin-whitening cosmetics. Several studies employed the structure of tyrosinase from Agaricus bisporus as a model enzyme. Recently, 98% of human genome proteins were elucidated by AlphaFold. Herein, the AlphaFold structure of human tyrosinase and the previous model were compared. Moreover, tyrosinase-related proteins 1 and 2 were included, along with inhibition studies employing kojic and cinnamic acids. Peptides are widely studied for their inhibitory activity of skin-related enzymes. Cyanophycin is an amino acid polymer produced by cyanobacteria and is built of aspartic acid and arginine; arginine can be also replaced by other amino acids. A new set of cyanophycin-derived dipeptides was evaluated as potential inhibitors. Aspartate–glutamate showed the strongest interaction and was chosen as a leading compound for future studies.

The nature of binding between bovine serum albumin (BSA) and the antidepressant tianeptine and a new series of esters derivatives were studied in this paper. The interactions with BSA were investigated by UV-Vis and fluorescence spectroscopy at three different temperatures. The fluorescence quenching experiments showed that BSA interactions with tianeptine could be dynamic while to its esters a static mechanism was observed. The results showed that tianeptine quenches the intrinsic fluorescence of BSA more efficiently than its esters due to the presence of the free acid portion. The number of binding sites determined by fluorescence spectroscopy is approximately equal to 1 indicating that there is one binding site between BSA tianeptine esters, but the presence of a second interaction site for tianeptine at higher temperatures could be not ruled out. Molecular docking calculations point out a strong affinity of tianeptine and its esters to the site IIA of protein, supporting the hypothesis of a static quenching mechanism.

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