structural-biology-analytical-chemistry-approaches-for-characterizing

Structural Biology and Analytical Chemistry Approaches for Characterizing <em>C</em>-Glycoside Metabolic Enzymes in Human Gut Microbiota

The gut microbiota has emerged as a key modulator of host health, particularly because of its capacity to metabolize dietary glycosides. While ...

production-sars-cov-2-virus-like-particle-system-to-investigate-viral

Production of a SARS-CoV-2 Virus-Like-Particle System to Investigate Viral Life Cycles <em>In Vitro</em>

The severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) virus-like particle (SC2-VLP) method offers a powerful and accessible tool for studying ...

Beijing University of Chinese Medicine

Baicalein, a famously effective component of the traditional Chinese medicine Rhizoma Huang Qin ( L.), has been proved to have potent neuroprotection and anti-platelet aggregation effects with few side effects. Meanwhile, recent studies have revealed that the introduction of amino acid to baicalein could improve its neuroprotective activity. In the present study, a series of novel baicalein amino acid derivatives were designed, synthesized, and screened for their neuroprotective effect against -butyl, hydroperoxide-induced, SH-SY5Y neurotoxicity cells and toxicity on the normal H9C2 cell line by standard methylthiazol tetrazolium (MTT) assay. In addition, all of the newly synthesized compounds were characterized by H-NMR, C-NMR, and high resolution mass spectrometry (HR-MS). The results showed that most of the compounds provided more potent neuroprotection than baicalein, and were equivalent to the positive drug edaravin. They showed no obvious cytotoxicity on normal H9C2 cells. Notably, the most active compound  displayed the highest protective effect (50% effective concentration (EC) = 4.31 μM) against -butyl, hydroperoxide-induced, SH-SY5Y neurotoxicity cells, which was much better than the baicalein (EC = 24.77 μM) and edaravin (EC = 5.62 μM). Further research on the chick chorioallantoic membrane (CAM) model indicated that compound  could significantly increase angiogenesis, which might promote neurovascular proliferation. The detection of apoptosis analysis showed that compound  could dramatically alleviate morphological manifestations of cell damage. Moreover, the benzyloxycarbonyl (cbz)-protected baicalein amino acid derivatives showed better neuroprotective activity than the -Butyloxy carbonyl (boc)-protected derivatives.

Synthesis of Novel Baicalein Amino Acid Derivatives and Biological Evaluation as Neuroprotective Agents.

The -glycosidic bond that connects the sugar moiety with aglycone is difficult to be broken or made due to its inert nature. The knowledge of -glycoside breakdown and synthesis is very limited. Recently, the enzyme DgpA/B/C cascade from a human intestinal bacterium PUE was identified to specifically cleave the -glycosidic bond of puerarin (daidzein-8--glucoside). Here we investigated how puerarin is recognized and oxidized by DgpA based on crystal structures of DgpA with or without substrate and biochemical characterization. More strikingly, we found that apart from being a -glycoside cleaving enzyme, DgpA/B/C is capable of efficiently converting - to -glycoside showing the activity as a structure isomerase. A possible mechanistic model was proposed dependently of the simulated complex structure of DgpB/C with 3″-oxo-daidzin and structure-based mutagenesis. Our findings not only shed light on understanding the enzyme-mediated -glycosidic bond breakage and formation, but also may help to facilitate stereospecific -glycoside synthesis in pharmaceutical industry.

Structural mechanism of a dual-functional enzyme DgpA/B/C as both a -glycoside cleaving enzyme and an - to -glycoside isomerase.

 an insufficient coat protein complex I (COPI) retrieval signal, the majority of SARS-CoV-2 spike (S) is resident in host early secretory organelles and a tiny amount is leaked out in cell surface. Only surface-exposed S can be recognized by B cell receptor (BCR) or anti-S therapeutic monoclonal antibodies (mAbs) that is the trigger step for B cell activation after S mRNA vaccination or infected cell clearance by S mAbs. Now, a drug strategy to promote S host surface exposure is absent. Here, we first combined structural and biochemical analysis to characterize S COPI sorting signals. A potent S COPI sorting inhibitor was then invented, evidently capable of promoting S surface exposure and facilitating infected cell clearance by S antibody-dependent cellular cytotoxicity (ADCC). Importantly, with the inhibitor as a probe, we revealed Omicron BA.1 S is less cell surface exposed than prototypes because of a constellation of S folding mutations, possibly corresponding to its ER chaperone association. Our findings not only suggest COPI is a druggable target against COVID-19, but also highlight SARS-CoV-2 evolution mechanism driven by S folding and trafficking mutations.

ArticleTotal : 2	Year
Publication title	2025
Publication title	2025

Article	Year
Synthesis of Novel Baicalein Amino Acid Derivatives and Biological Evaluation as Neuroprotective Agents. Molecules (Basel, Switzerland)\| PubMed ID: 31601055	2019
Structural mechanism of a dual-functional enzyme DgpA/B/C as both a -glycoside cleaving enzyme and an - to -glycoside isomerase. Acta pharmaceutica Sinica. B\| PubMed ID: 36815035	2023
SARS-CoV-2 spike host cell surface exposure promoted by a COPI sorting inhibitor. Acta pharmaceutica Sinica. B\| PubMed ID: 37360012	2023

Shuqi Zhou

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