Biology subjects

Palomo, J. M.

Publications and source records attributed to Palomo, J. M..

2 recordsLinked to original sources

bioRxiv2023

Inhibition of SARS-CoV-2 3CLpro in vitro by chemically modified tyrosinase from Agaricus bisporus

Antiviral compounds are crucial to controlling the SARS-CoV-2 pandemic. Approved drugs have been tested for their efficacy against COVID-19, and new pharmaceuticals are being developed as a complementary tool to vaccines However, there are not any effective treatment against this disease yet. In this work, a cheap and fast purification method of natural tyrosinase from Agaricus bisporus fresh mushrooms was developed in order to evaluate the potential of this enzyme as a therapeutic protein by the inhibition of SARS-CoV-2 3CLpro protease activity in vitro. Tyrosinase showed a mild inhibition of 3CLpro of around 15%. Thus, different variants of this protein were synthesized through chemical modifications, covalently binding different tailor-made glycans and peptides to the amino terminal groups of the protein. These new tyrosinase conjugates were purified and characterized by circular dichroism and fluorescence spectroscopy analyses, and their stability under different conditions. Then all these tyrosinase conjugates were tested in 3CLpro protease inhibition. From them, the conjugate between tyrosinase and dextran-aspartic acid (6kDa) polymer showed the highest inhibition, with an IC50 of 2.5 g/ml and IC90 of 5 g/ml, results that highlight the potential use of modified tyrosinase as a therapeutic protein and opens the possibility of developing this and other enzymes as pharmaceutical drugs against diseases.

biochemistry↗

bioRxiv2020

Tyrosinase from mushroom Agaricus bisporus as an inhibitor of the Hepatitis C virus

Tyrosinases from both a commercial semi-purified Agaricus bisporus protein extract and directly isolated from white mushroom have been demonstrated to show antiviral activity against the Hepatitis C virus for the first time. The well-known tyrosinase from A. bisporus (TyrAB) of 45kDa and a newly discovered 50-kDa isoform from this tyrosinase (Tyr50kDa) have been tested. Cell toxicity and antiviral activity of tyrosinases in cultured Huh 5-2 liver tumor cells transfected with a replicon system (a plasmid that includes all non-structural Hepatitis C virus proteins and replicates autonomously) was determined. Native TyrAB was able to inhibit the replication of the hepatitis C virus without inducing toxicity in liver cells. In addition, the post-translational isoform of Tyr50kDa showed higher antiviral capacity than the former (up to 10 times greater), also exhibiting 10 times higher activity than the commercial drug Ribavirin(R). This antiviral activity was directly proportional to the enzymatic activity of tyrosinases, since no antiviral capacity was observed for the inactive enzymes. The tyrosinases approach could represent a new antiviral inhibition mechanism, through a catalytic mechanism of selective hydroxylation of key role tyrosine residues in viral proteases. The tyrosinases directly extracted from fresh mushrooms (containing both tyrosinases) showed similar antiviral activity and, therefore, might provide low-cost drugs for the treatment of hepatitis C.

microbiology↗