Correlation Analysis of Key Residue Sites between Computational-Aided Design Thermostability d-Amino Acid Oxidase and Ancestral Enzymes.

The d-amino acid oxidase (DAAO) from Rhodotorula taiwanensis has proven to have great potential for applications due to its excellent catalytic kinetic parameters. However, its poor thermal stability has limited its performance in biocatalysis. Herein, starting from the variant SHVG of RtwDAAO, this study employed a comprehensive computational design approach for protein stability engineering, resulting in positive substitutions at specific sites (A43S, T45M, C234L, E195Y). The generated variant combination, SHVG/SMLY, exhibited a significant synergistic effect, leading to an extension of the half-life and Tmapp. The ancestral sequence reconstruction revealed the conservation of the variant sites. The association of the variant sites with the highly stable ancestral enzyme was further explored. After determining the contribution of the variant sites to thermal stability, it was applied to other homologous sequences and validated. Molecular dynamics simulations indicated that the increased hydrophobicity of the variant SHVG/SMLY was a key factor for the increased stability, with strengthened intersubunit interactions playing an important role. In addition, the physical properties of the amino acids themselves were identified as crucial factors for thermal stability generality in homologous enzymes, which is important for the rapid acquisition of a series of stable enzymes.

Efficient Production of 3-Amino-2-Hydroxy Acetophenone by Multi-Enzyme Biosynthesis.

We developed a synthetic route for producing 3-amino-2-hydroxy acetophenone (3AHAP) from m-nitroacetophenone (3NAP) using an in vitro approach. Various reaction systems were evaluated, and a direct reaction method with crude enzyme and supersaturated substrates for optimal catalytic efficiency was chosen. The reaction system included three enzymes and was enhanced by adjusting enzyme molar ratios and optimizing ribosomal binding sites. We performed substrate docking and alanine scanning to identify key sites in the enzymes nitrobenzene nitroreductase (nbzA) and hydroxylaminobenzene mutase (habA). The optimal mutant was obtained through site-directed mutagenesis, and incorporated into the reaction system, resulting in increased product yield. After optimization, the yield of 3AHAP increased from 75 mg/L to 580 mg/L within 5 hours, the highest reported yield using biosynthesis. This work provides a promising strategy for the efficient and sustainable production of 3AHAP, which has critical applications in the chemical and pharmaceutical industries.

[Regulatory mechanism of heat shock protein 90 on autophagy-related transcription factor EB in human hepatocellular carcinoma cells].

This study was aimed to investigate the regulatory mechanism of heat shock protein 90 (Hsp90) on transcription factor EB (TFEB) during autophagy in liver cancer cells. Human hepatocellular carcinoma cell line HepG2 was treated with Hsp90 N- and C-terminal inhibitors (STA9090 and Novobiocin), respectively. Western blot and RT-PCR were used to detect the expression levels of TFEB and autophagy-related proteins. Chromatin immunoprecipitation (ChIP) assay was used to observe the ability of Hsp90α binding to the TFEB proximal promoter region. The double-luciferase gene reporter experiment was used to determine the activity of TFEB promoter. The results showed that hypoxia induced up-regulation of TFEB protein and mRNA expression levels in the HepG2 cells. The protein expression levels of TFEB, LC3 and P62 were down-regulated significantly by either STA9090 or Novobiocin, under both normoxic and hypoxic conditions. Transfection of Hsp90α-overexpressing plasmids up-regulated TFEB protein levels in either wild-type or Hsp90α knockout HepG2 cells. Hsp90 bound to the TFEB proximal promoter region and was involved in regulating TFEB transcriptional process. Whereas both STA9090 and Novobiocin inhibited Hsp90 to bind to the TFEB proximal promoter region, and decreased the activity of TFEB promoter. These results suggest that Hsp90 promotes TFEB transcription in human hepatocellular carcinoma cells by binding to the proximal promoter region, thereby up-regulating the expression levels of autophagy-related proteins.

[Analysis of Human Herpes Viruses-Activated Infection Spectra in Patients with Various Immunodeficiencies].

OBJECTIVE: To study the epidemiologic characteristics of human herpes virus (HHV) activated infection in the diseases of blood system and patients received allo-HSCT by statistically analyzing the screening results of 8 human herpes viruses (HHVs) of 4164 patients in Hebei Yanda LU Dao-Pei Hospital from 2012 to 2017. METHODS: PCR was used to screen 8 HHVs. RESULTS: Two thousand and fifty-two patients (49.28%) were HHV-positive among 4164 patients screened. Among these patients screened, the infection spectra of 8 human HHVs in hematological diseases as well as patients received allogeneic hematopoietic stem cell transplantation of totally 2994 patients were summarized as follows: the positive rate of EBV (29.49%) was the highest, that of HCMV (23.15%), HHV-6 was 18.77% and HHV-7 was 17.64%, while the remaining 4 HHVs all≤2.1%. The rate of co-infection of various HHVs was significantly higher than that of single infection of HHV among all these disease groups except familial hemophagocytic lymphohistiocytosis, for which single EBV infection was the most common. The differences of positive rates among these 8 human HHVs in hematological diseases as well as patients received allogeneic hematopoietic stem cell transplantation were statistically significant by Chi-square test of R*C tables (χ2=54.99, P＜0.05). For each HHV, the differences of positive rates among the above-mentioned disease groups were also statistically significant except HHV-8 (P＜0.05). CONCLUSION: The patients with various blood diseases have different activated infection spectra of HHVs. EBV, HCMV, HHV-6 and HHV-7 are most common in HHVs infection. Different HHVs infections correlate with different hematologion diseases.

Food-drug interaction of (-)-epigallocatechin-3-gallate on the pharmacokinetics of irinotecan and the metabolite SN-38.

The aim of the present study was to investigate the effect of (-)-epigallocatechin-3-gallate (EGCG) on the pharmacokinetics of irinotecan (CPT-11) and its metabolite SN-38. EGCG was potentially used to modulate the ATPase activity of P-glycoprotein (P-gp). Experimental Sprague-Dawley rats were treated with EGCG (20mg/kg, i.v.) 10min before CPT-11 (10mg/kg, i.v.) administration, whereas the control group received CPT-11 (10mg/kg, i.v.) only. The biological samples were prepared by the protein precipitation and detected by HPLC-fluorescence detection which provided a good separation of CPT-11 and SN-38 within 10min. The pharmacokinetic data indicate that the area under the plasma concentration-time curves (AUC) of CPT-11 and SN-38 were increased by 57.7 and 18.3%, and AUC in bile were decreased by 15.8 and 46.8%, respectively, for the group pretreated with EGCG. The blood to bile distribution ratio (AUC(bile)/AUC(blood)) was significantly reduced after group coadministration of EGCG, it can be seen that the bile efflux transport system of CPT-11 and SN-38 may be markedly reduced by the treatment of EGCG which plays the role of P-gp inhibitor. In conclusion, EGCG was found to inhibit the transport of CPT-11 and SN-38 into the biliary elimination and their half-lives in plasma could be substantially prolonged. Based on the food-drug interaction, persons taking daily nutritional supplements should be warned of this interaction possibility.

Effect of cyclosporin A on the brain regional distribution of doxorubicin in rats.

Doxorubicin (DOX) is an anthracycline antibiotic that possesses broad-spectrum antineoplastic activity, and is one of the most important anticancer agents. The purpose of this study was to investigate the effects of cyclosporine A (CsA) on the brain regional distribution of DOX and its liposome DOX formulation (Lipo-Dox). Liquid chromatography with tandem mass spectrometry (LC-MS/MS) was used to measure DOX in rat plasma and in various brain regions (cerebral cortex, hippocampus, striatum, midbrain, cerebellum, and the rest of brain). Good linearity was achieved over the 5-5000ng/mL range, with coefficients of correlation greater than 0.995. The limit of quantification for doxorubicin was 5ng/mL. This study was divided into the following four groups: DOX alone, DOX+CsA, Lipo-Dox alone and Lipo-Dox+CsA. After administering DOX (5mg/kg, i.v.) alone and DOX+CsA (10mg/kg, i.v.), it was undetectable in various brain regions. When the same dose of Lipo-Dox (5mg/kg, i.v.) and Lipo-Dox+CsA (10mg/kg, i.v.) were given individually, the plasma level and the brain regional level of DOX were much greater than those of DOX given alone. These results indicate that Lipo-Dox prolongs the DOX level in plasma and enhances brain distribution of DOX. The disposition of DOX might be regulated by P-glycoprotein.

Transdermal delivery of tea catechins and theophylline enhanced by terpenes: a mechanistic study.

Using in vitro and in vivo techniques, terpenes were evaluated as enhancers to improve the skin permeation of therapeutically active agents derived from tea, including tea catechins and theophylline. The in vitro permeation was determined by Franz cells. The skin deposition and subcutaneous amounts of drugs sampled by microdialysis were evaluated in vivo. Terpenes varied in their activities of enhancing drug permeation. The oxygen-containing terpenes were effective enhancers of drug permeation, whereas the hydrocarbon terpenes were much less efficient. Oxygen-containing terpenes with a bicyclic structure had reduced enhancing activity. Terpenes enhanced tea catechin permeation to a much greater degree than they did theophylline. The isomers of (+)-catechin and (-)-epicatechin showed different permeation behaviors when incorporated with terpenes. In the in vivo status, terpenes promoted the skin uptake but not the subsequent subcutaneous concentration of (-)-epigallocatechin gallate (EGCG). Both increased skin/vehicle partitioning and lipid bilayer disruption of the stratum corneum (SC) contributed the enhancing mechanisms of terpenes for topically applied tea catechins and theophylline based on the experimental results from the partition coefficient and transepidermal water loss (TEWL). alpha-Terpineol was found to be the best enhancer for catechins and theophylline. The high enhancement by alpha-terpineol was due to macroscopic perturbation of the SC and the biological reaction in viable skin as evaluated by TEWL and colorimetry.

Pharmacokinetics of (-)-epigallocatechin-3-gallate in conscious and freely moving rats and its brain regional distribution.

A liquid chromatography technique coupled with tandem mass spectrometry (LC-MS/MS) electrospray ionization was used to measure (-)-epigallocatechin-3-gallate (EGCG) in rat plasma. This method was applied to investigate the pharmacokinetics of EGCG in a conscious and freely moving rat by an automated blood sampling device. Multiple reaction monitoring (MRM) was used to monitor the transition of the deprotonated molecule m/z of 457 [M - H]- to the product ion 169 for EGCG and the m/z of 187 to 164 for the internal standard. The limit of quantification (LOQ) of EGCG in rat plasma was determined to be 5 ng/mL, and the linear range was 5-5000 ng/mL. The protein binding of EGCG in rat plasma was 92.4 +/- 2.5%. The brain distribution result indicated that EGCG may potentially penetrate through the blood-brain barrier at a lower rate. The disposition of EGCG in the rat blood was fitted well by the two-compartmental model after intravenous administration (10 mg/kg, iv). The elimination half-life of EGCG was 62 +/- 11 and 48 +/- 13 min for intravenous (10 mg/kg) and oral (100 mg/kg) administration, respectively. The pharmacokinetic data indicate that the oral bioavailability of EGCG in a conscious and freely moving rat was about 4.95%.