Publications by authors named "Chul-Ho Yun"

Ethanol is environmentally friendly, not hazardous, and can be produced from renewable sources. In this study, ethanol was applied as a cosolvent for the tyrosinase-catalyzed synthesis of catechol compounds from phenolic compounds, which are abundant in fruit pomace. To investigate the cosolvent function of ethanol on tyrosinase, six types of tyrosinase from Priestia megaterium and water-insoluble phenolic substrates (i.

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Proton pump inhibitors (PPIs), metabolized by cytochrome P450 (P450) enzymes, are widely used to inhibit gastric acid secretion. This study investigated CYP116B46, a self-sufficient monooxygenase with a reductase domain, to elucidate its interaction with ilaprazole, a PPI. Binding assays and docking simulations indicate that CYP116B46 serves as a suitable model for studying PPI metabolism.

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The monooxygenase activity of engineered CYP102A1 on α-terpineol was investigated. CYP102A1 M850 mutant (F11Y/R47L/D68G/F81I/F87V/E143G/L188Q/E267V/H408R) showed the highest catalytic activity toward α-terpineol among the engineered mutants produced by random mutagenesis. The major product (P1) of α-terpineol, p-menth-1-ene-3,8-diol, was characterized by high-performance liquid chromatography, gas-chromatography mass spectrometry, and nuclear magnetic resonance spectroscopy.

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Perillyl alcohol (POH) is a secondary metabolite of plants. POH and its derivatives are known to be effective as an anticancer treatment. In this study, oxidative derivatives of POH, which are difficult to synthesize chemically, were synthesized using the engineered bacterial cytochrome P450 BM3 (CYP102A1) as a biocatalyst.

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Recombinant cytochrome P450 monooxygenases possess significant potential as biocatalysts, and efforts to improve heme content, electron coupling efficiency, and catalytic activity and stability are ongoing. Domain swapping between heme and reductase domains, whether natural or engineered, has thus received increasing attention. Here, we successfully achieved split intein-mediated reconstitution (IMR) of the heme and reductase domains of P450 BM3 both in vitro and in vivo.

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pv. () causes a devastating bacterial leaf blight in rice. Here, the antimicrobial effects of D-limonene, L-limonene, and its oxidative derivative carveol against were investigated.

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CYP102A1 from is an important enzyme in biotechnology, because engineered CYP102A1 enzymes can react with diverse substrates and produce human cytochrome P450-like metabolites. Therefore, CYP102A1 can be applied to drug metabolite production. Terpinen-4-ol is a cyclic monoterpene and the primary component of essential tea tree oil.

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Rabeprazole is a common type of proton pump inhibitor (PPI) used to treat various peptic disorders. Unlike most PPI drugs, rabeprazole is spontaneously reduced to rabeprazole sulfide (thioether) when it is given to patients. As a result, rabeprazole sulfide is considered one of the active metabolites of rabeprazole.

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Axl is a tyrosine kinase receptor, a negative regulator for innate immune responses and inflammatory bowel disease (IBD). The gut microbiota regulates intestinal immune homeostasis, but the role of Axl in the pathogenesis of IBD through the regulation of gut microbiota composition remains unresolved. In this study, mice with DSS-induced colitis showed increased Axl expression, which was almost entirely suppressed by depleting the gut microbiota with antibiotics.

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CYP102A1 is a promiscuous bacterial cytochrome P450 (CYP or P450) known for its diverse substrates and comparable activity with human P450 enzymes. The development of CYP102A1 peroxygenase activity can contribute significantly to human drug development and drug metabolite production. Peroxygenase has recently emerged as an alternative to a dependency of P450 on NADPH-P450 reductase and NADPH cofactor and gives more opportunity for practical application.

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Phloretin and its glycoside phlorizin have been reported to prevent obesity induced by high-fat diet (HFD), but the effect of 3-OH phloretin, a catechol metabolite of phloretin, has not been investigated. In this study, we investigated the anti-obesity effects of phloretin and 3-OH phloretin in HFD-fed mice. The body weight gain induced by HFD was more inhibited by administration of 3-OH phloretin than by phloretin.

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Niclosamide has been proposed as a possible candidate for a Covid-19 drug. However, the metabolites of niclosamide are difficult to investigate because they are usually not available commercially or they are quite expensive in the commercial market. In this study, the major metabolite of niclosamide in human liver microsomes (HLMs) was confirmed to be 3-OH niclosamide.

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Tenatoprazole, a newly developed proton pump inhibitor candidate, was developed as an acid inhibitor for gastric acid hypersecretion disorders such as gastric ulcer and reflux esophagitis. It is known that tenatoprazole is metabolized to three major metabolites of 5'-hydroxy tenatoprazole, tenatoprazole sulfide, and tenatoprazole sulfone in human liver, primarily catalyzed by CYPs 2C19 and 3A4. While CYP2C19 prefers the hydroxylation of tenatoprazole at C-5' position, CYP3A4 is mainly involved in sulfoxidation reaction to make tenatoprazole sulfone.

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Article Synopsis
  • The use of NADPH-dependent hydroxylases in transforming chemicals to create more soluble or valuable products is gaining interest, but their industrial use is restricted due to the high cost of NADPH.
  • Researchers expressed and purified two recombinant isocitrate dehydrogenases (IDHs) from different sources, yielding over 850 mg/L, and found they worked effectively with NADPH-consuming systems, specifically paired with cytochrome P450 BM3.
  • The IDHs can serve as viable alternatives for NADPH regeneration systems and may also be used in genetic fusions with other NADPH-dependent enzymes, enabling more efficient biocatalysts that regenerate NADPH within a single polypeptide.
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Enzymes are the catalyst of choice for highly selective reactions, offering nature-inspired approaches for sustainable chemical synthesis. Oxidative enzymes (, monooxygenases, peroxygenases, oxidases, or dehydrogenases) catalyze a variety of enantioselective oxyfunctionalization and dehydrogenation reactions under mild conditions. To sustain the catalytic cycles of these enzymes, constant supply with or withdrawal of reducing equivalents (electrons) is required.

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Tyrosinases, type-3 copper proteins responsible for melanin formation in various organisms, have considerable potential to produce bioactive catechol derivatives such as 3,4-dihydroxy-L-phenylalanine (L-DOPA). They catalyze the ortho-hydroxylation of L-tyrosine to L-DOPA via monophenolase activity and the subsequent oxidation of L-DOPA to dopaquinone through diphenolase activity, which then spontaneously converts to melanin. In this study, six novel Bacillus megaterium strains, GJ802, GJ803, DY801, DY802, DY804, and DY805, were isolated from rice straw in South Korea.

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Statins inhibit the 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMG-CoA reductase), which is the rate-limiting enzyme in cholesterol biosynthesis. Statin therapy reduces morbidity and mortality in those who are at high risk of cardiovascular disease. Monacolin J is a statin compound, which is an intermediate in the lovastatin biosynthesis pathway, in the fungus .

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Article Synopsis
  • The study focuses on the biodegradation of polystyrene (PS), a major plastic waste that is notoriously hard to break down, using specific bacterial cultures found in soil.
  • Two bacterial strains, Pseudomonas lini JNU01 and Acinetobacter johnsonii JNU01, were identified as effective in growing and degrading PS when cultivated in a nutrient medium with PS as the sole carbon source.
  • Various analytical techniques, including spectroscopy and microscopy, confirmed the biodegradation process and identified the alkane-1-monooxygenase enzyme (AlkB) in A. johnsonii JNU01 as key in facilitating PS breakdown, highlighting the potential of these microbes in managing
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Phlorizin is the most abundant glucoside of phloretin from the apple tree and its products. Phlorizin and its aglycone phloretin are currently considered health-beneficial polyphenols from apples useful in treating hyperglycemia and obesity. Recently, we showed that phloretin could be regioselectively hydroxylated to make 3-OH phloretin by CYP102A1 and human P450 enzymes.

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Article Synopsis
  • The cover features a joint research group from KAIST and CNU, led by Prof. Chan Beum Park and Prof. Chul-Ho Yun.
  • The study highlights how flavin mononucleotide, a natural photosensitizer, combined with visible light can create an eco-friendly and cost-effective method for P450-catalyzed reactions.
  • More details about the research can be found at the provided DOI: 10.1002/cssc.202100944.
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Plastic contamination currently threatens a wide variety of ecosystems and presents damaging repercussions and negative consequences for many wildlife species. Sustainable plastic waste management is an important approach to environmental protection and a necessity in the current life cycle of plastics in nature. Plastic biodegradation by microorganisms is a notable possible solution.

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Bottom-up micropatterning or nanopatterning can be viewed as the localization of target molecules to the desired area of a surface. A majority of these processes rely on the physical adsorption of ink-like molecules to the paper-like surface, resulting in unstable immobilization of the target molecules owing to their noncovalent linkage to the surface. Herein, successive single nick-sealing facilitated the covalent immobilization of individual DNA molecules at defined positions on a dendron-coated silicon surface using atomic force microscopy.

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Article Synopsis
  • Photobiocatalysis is an eco-friendly method that utilizes solar energy to facilitate redox enzymatic reactions without the need for expensive cofactors.
  • A new system was developed using natural flavins as a photosensitizer to drive human cytochrome P450 (CYP) reactions with visible light, showcasing its effectiveness both in vitro and in whole-cell systems.
  • The study found that various factors like substrate type and the presence of catalase influence the photobiocatalytic activity of CYP2E1, indicating broad potential for applying this solar-powered method to other human CYPs.
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Triggering receptor expressed on myeloid cells 2 (TREM2) is a cell surface receptor expressed on macrophages, microglial cells, and pre-osteoclasts, and that participates in diverse cellular function, including inflammation, bone homeostasis, neurological development, and coagulation. In spite of the indispensable role of the TREM2 protein in the maintenance of immune homeostasis and osteoclast differentiation, the exact ligand for TREM2 has not yet been identified. Here, we report a putative TREM2 ligand which is secreted from MC38 cells and identified as a cyclophilin A (CypA).

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Ethnopharmacological Relevance: Shengmai San (SMS) has been commonly used as a traditional Chinese medicine for the treatment of cardiovascular disorders, of which drug interactions need to be assessed for the safety concern. There is little evidence for the alterations of hepatic and intestinal drug-metabolizing enzymes after repeated SMS treatments to assess drug interactions.

Aim Of The Study: The studies aim to illustrate the effects of repeated treatments with SMS on cytochrome P450s (CYPs), reduced nicotinamide adenine dinucleotide (phosphate)-quinone oxidoreductase (NQO), uridine diphosphate-glucuronosyltransferase (UGT), and glutathione S-transferase (GST) using in vivo rat model.

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