Cloning and heterologous expression of a hydrophobin gene Ltr. hyd from the tiger milk mushroom Lentinus tuber-regium in yeast-like cells of Tremella fuciformis

Background: Hydrophobins are small proteins secreted by filamentous fungi, which show a highly surface activity. Because of the signally self-assembling abilities and surface activities, hydrophobins were considered as candidates in many aspects, for example, stabilizing foams and emulsions in food products. Lentinus tuber-regium, known as tiger milk mushroom, is both an edible and medicinal sclerotium-producing mushroom. Up to now, the hydrophobins of L. tuber-regium have not been identified. Results: In this paper, a Class I hydrophobin gene, Ltr.hyd, was cloned from L. tuber-regium and expressed in the yeast-like cells of Tremella fuciformis mediated by Agrobacterium tumefaciens. The expression vector pGEH-GH was under the control of T. fuciformis glyceraldehyde-3-phosphate dehydrogenase gene (gpd) promoter. The integration of Ltr.hyd into the genome of T. fuciformis was confirmed by PCR, Southern blot, fluorescence observation and quantitative real-time PCR (qRT-PCR). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that recombinant hydrophobin rLtr.HYD with an expected molecular mass of 13 kDa was extracted. The yield of rLtr.HYD was 0.66 mg/g dry weight. The emulsifying activity of rLtr.HYD was better than the typical food emulsifiers sodium caseinate and Tween 20. Conclusions: We evaluated the emulsifying property of hydrophobin Ltr.HYD, which can be potentially used as a food emulsifier.

Effects of mineral trioxide aggregate, BiodentineTM and calcium hydroxide on viability, proliferation, migration and differentiation of stem cells from human exfoliated deciduous teeth

Abstract Objective: The aim of the study was to evaluate the effects of the capping materials mineral trioxide aggregate (MTA), calcium hydroxide (CH) and BiodentineTM (BD) on stem cells from human exfoliated deciduous teeth (SHED) in vitro. Material and Methods: SHED were cultured for 1 - 7 days in medium conditioned by incubation with MTA, BD or CH (1 mg/mL), and tested for viability (MTT assay) and proliferation (SRB assay). Also, the migration of serum-starved SHED towards conditioned media was assayed in companion plates, with 8 μm-pore-sized membranes, for 24 h. Gene expression of dentin matrix protein-1 (DMP-1) was evaluated by reverse-transcription polymerase chain reaction. Regular culture medium with 10% FBS (without conditioning) and culture medium supplemented with 20% FBS were used as controls. Results: MTA, CH and BD conditioned media maintained cell viability and allowed continuous SHED proliferation, with CH conditioned medium causing the highest positive effect on proliferation at the end of the treatment period (compared with BD and MTA) (p<0.05). In contrast, we observed increased SHED migration towards BD and MTA conditioned media (compared with CH) (p<0.05). A greater amount of DMP-1 gene was expressed in MTA group compared with the other groups from day 7 up to day 21. Conclusion: Our results show that the three capping materials are biocompatible, maintain viability and stimulate proliferation, migration and differentiation in a key dental stem cell population.

Clone and expression of CpGAPDH gene in Codonopsis pilosula / 中国中药杂志

GAPDH(glyceraldehyde-3-phosphate dehydrogenase) gene is a key enzyme gene in carbohydrate metabolism and always used as reference gene. To clarify and complete the biosynthetic pathway of polysaccharide, the GAPDH gene in Codonopsis pilosula, named CpGAPDH, was cloned according to the transcriptome of pilosula, using the GAPDH gene in potato as query. The CpGAPDH contained a 1 014 bp open reading frame(ORF) and encoded a protein with 337 amino acids. Bioinformatic analysis clearly suggested that CpGAPDH shared high similarity with GAPDH among other plants, and had the closest relatives to potato and danshen. The predicted protein did not have signal peptide, which indicated that it might be located in the cytoplasm. According to the existing of several phosphorylation sites and the conserved domains analysis, we predicted that it belonged to Gp_dh_N superfamily. Prokaryotic expression showed that the recombinant expressed a 44.3 kDa protein, which was corresponding to the theoretical relative molecular mass. However, the relative transcript level of the CpGAPDH did not have significant differences in different tissues and roots at different developmental stages of pilosula. Moreover, the stability of the CpGAPDH was analyzed by BestKeeper, geNorm, and NormFinder and RefFinder software, which showed that the CpGAPDH was more stable and could be used as a new reference gene. All these lay a foundation for the expression analysis of the gene relative to the polysaccharide synthesis.

Homocysteine induces glyceraldehyde-3-phosphate dehydrogenase acetylation and apoptosis in the neuroblastoma cell line Neuro2a

High plasma levels of homocysteine (Hcy) promote the progression of neurodegenerative diseases. However, the mechanism by which Hcy mediates neurotoxicity has not been elucidated. We observed that upon incubation with Hcy, the viability of a neuroblastoma cell line Neuro2a declined in a dose-dependent manner, and apoptosis was induced within 48 h. The median effective concentration (EC50) of Hcy was approximately 5 mM. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) nuclear translocation and acylation has been implicated in the regulation of apoptosis. We found that nuclear translocation and acetylation of GAPDH increased in the presence of 5 mM Hcy and that higher levels of acetyltransferase p300/CBP were detected in Neuro2a cells. These findings implicate the involvement of GAPDH in the mechanism whereby Hcy induces apoptosis in neurons. This study highlights a potentially important pathway in neurodegenerative disorders, and a novel target pathway for neuroprotective therapy.

Correlation between five RNA markers of rat's skin and PMI at different temperatures / 法医学杂志

OBJECTIVE@#To explore the correlation between postmortem interval (PMI) and five RNA markers of rat's skin--β-actin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 18S ribosomal RNA(18S rRNA), 5S ribosomal RNA (5S rRNA), and microRNA-203 (miR-203), at different temperatures.@*METHODS@#Eighteen SD rats were randomly divided into three environmental temperature groups: 4 °C, 15 °C and 35 °C, respectively. Skin samples were taken at 11 time points from 0 h to 120 h post-mortem. The total RNA was extracted from the skin samples and the five RNA levels were detected by real-time fluorescent quantitative PCR. Proper internal reference was selected by geNorm software. Regression analysis of the RNA markers was conducted by GraphPad software.@*RESULTS@#5S rRNA and miR-203 were most suitable internal references. A good linear relationship between PMI and RNA levels (β-actin and GAPDH) was observed in two groups (4 °C and 15 °C), whereas the S type curve relationship between the expression levels of the two markers (β-actin and GAPDH) and PMI was observed in the 35 °C group. The partial linear relationship between 18S rRNA and PMI was observed in the groups (15 °C and 35 °C).@*CONCLUSION@#Skin could be a suitable material for extracting RNA. The RNA expression levels of β-actin and GAPDH correlate well with PMI, and these RNA markers of skin tissue could be additional indice for the estimation of PMI.

Relationship between PMI and relative expression of myocardial various RNAs in rats died of different causes / 法医学杂志

OBJECTIVE@#To observe the changes of relative expression of myocardial various RNAs in rats died of different causes and their relationship with PMI.@*METHODS@#The rat models were established in which the rats were sacrificed by broken neck, asphyxia, and hemorrhagic shock. Total RNAs were extracted from myocardium. The quantitative real time PCR was used to calculate threshold cycle values of RNAs including glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-actin, inducible nitric oxide synthase (iNOS), hypoxia-inducible factor-1 (HIF-1), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and U6 small nuclear RNA (U6 snRNA) and to study the changes of the relative expressions of various indexes with PMI.@*RESULTS@#U6 snRNA with stable expression level could be used as appropriate internal control. In the early PMI, the relative expression of GAPDH, HIF-1, iNOS, TNF-alpha, and IL-6 more characteristically increased in groups of asphyxia and hemorrhagic shock than in group of broken neck, but the quantity of beta-actin decreased in all groups. In the late PMI, all the relative expressions significantly declined in correlation with the degradation of RNA.@*CONCLUSION@#The characteristic changes of each RNA expression can be used as references to estimate PMI in deaths by different causes.

The construction and the expression of V5 epitope fused human androgen receptor vector in the yeast cell / 生物医学工程学杂志

When we try to establish the gene recombinant yeast cell to screen the androgenic endocrine disruptors, the key procedure is the androgen receptor (AR) expression in the yeast cell. For this purpose, we obtained the GPD (glyceraldehyde-3-phosphote dehydrogenase) promoter from the yeast genosome of W303-1A using PCR system and inserting it into Swa I and BamH I sites of pYestrp2. The new constructed vector was named pGPD. The V5 epitope tag DNA with a 5'-BamH I and a 3'-EcoR I sticky end was cloned into the corresponding site of the pGPD vector to yield the vector of pGPDV5. The 2 723 bp full length AR ORF amplified by PCR from pcDNA3.1/AR was fused to V5 epitope tag DNA in pGPDV5 to give the AR yeast expression vector of pGPDV5/AR. This fused vector was transformed into the yeast cell (W303-1A). Western blot was used to detect the V5 fused protein of AR, in the protocol of which the primary monoclonal antibody (IgG(2a)) of mouse anti-V5 and the polyclonal secondary antibody of goat anti-mouse (IgG) linked to horseradish peroxidase (HRP) were used to detect the specific protein in the given sample of the transformed yeast extract. The result showed that the fused protein of AR was expressed successfully in the yeast cell.

Construction of a recombinant plasmid harbouring the glyceraldenyde-3-phosphate dehydrogenase gene of periodic Brugia malayi and observation on DNA immunity.

Purpose: Controlling and eliminating lymphatic filariasis will require further research of preventative measures and implementation. Parasite is dependent on glycolysis for ATP production. The glycolytic enzyme glyceraldenyde-3-phosphate dehydrogenase (GAPDH) plays an important role in glycolysis and therefore is either a potential target for anti-parasite drug development or a vaccine candidate. Therefore, we tried to investigate the DNA vaccine-elicited immune responses in BALB/c mice. Materials and Methods: We cloned a gene encoding the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from periodic Brugia malayi into vector pcDNA3.1. Mice were injected at a dosage of 100 μg recombinant plasmid DNA with CpG intramuscular injection and immunized three times at 2-week intervals. pcDNA3.1 and normal saline were used as control. The tissue of muscles at the 4 weeks after the third injection was collected and target genes were detected using RT-PCR. The humoral responses elicited in mice by inoculation with the recombinant plasmid pcDNA3.1-BmGAPDH were detected using a standard ELISA. Two weeks after the third immunization, stimulation index (SI) was measured using the MTT method and the level of secreted IL-4 and INF-g were detected using ELISA. Results: Specific gene fragment coding GAPDH was amplified and the recombinant plasmid pcDNA3.1-BmGAPDH was constructed. Post-challenge sera from the mice immunized with the DNA vaccine had specific antibody titres of 1:1600 to 1:6400, and the highest titre was observed in the mice that were inoculated by pcDNA3.1-BmGAPDH/CpG at 6 weeks. At 4 weeks after immunization, the spleens of the mice were obviously enlarged. The proliferation of spleen T lymphocytes seen on the MTT assay was higher in the pcDNA3.1-BmGAPDH group than in the control group (P value <0.05). The levels of IL-4 and INF-g in serums from the immunized mice were significantly higher than that of the control (P value <0.05). Conclusions: We conclude that the recombinant eukaryotic plasmid pcDNA3.1-BmGAPDH could elicit humoral and cellular immune responses in mice.

Application of the mammalian glyceraldehyde-3-phosphate dehydrogenase gene for sample quality control in multiplex PCR for diagnosis of leishmaniasis

Leishmaniasis is a neglected disease endemic in five continents. It is a severe disease that may lead to death, and its early detection is important to avoid severe damage to affected individuals. Molecular methods to detect Leishmania are considered alternatives to overcome the limitations presented by conventional methods. The aim of this study was to develop multiplex PCR systems able to detect small amounts of target DNA of Leishmania infantum and Leishmania braziliensis, and the gene coding for glyceraldehyde-3-phosphate dehydrogenase (G3PD) in mammals, enabling quality evaluation of the sample simultaneously with detection of the specific target. The systems created for G3PD recognition were combined with detection systems for L. infantum and L. braziliensis to compose multiplex PCR systems for visceral (mVL) and cutaneous (mACL) leishmaniasis diagnosis. The multiplex PCR systems developed were assessed in blood samples from five different species of mammal reservoirs involved in the disease cycle in Brazil, and 96 and 52 human samples from patients with suspected visceral leishmaniasis (VL) and cutaneous leishmaniasis (ACL), respectively. Three G3PD detection systems were created (G3PD1, G3PD2 and G3PD3) with different product sizes, G3PD2 was chosen for the formation of multiplex PCR systems. The two multiplex PCR systems (mVL and mACL) were reproducible in all species evaluated. Results of test samples (sensitivity, specificity and efficiency) suggest its use in routine diagnosis, research activities in medicine and veterinary medicine. Additionally, the systems designed to detect the G3PD gene are capable of combining with other targets used for molecular diagnosis of infectious diseases. Concerning leishmaniasis, the multiplex PCR systems can be used in epidemiological studies for the detection of new and classic reservoirs, which may contribute to the reliability of results and development of actions to control the disease.(AU)

Differentially expressed proteins on postoperative 3 days healing in rabbit Achilles tendon rupture model after early kinesitherapy / 中华创伤杂志(英文版)

<p><b>OBJECTIVES</b>Surgical repair of Achilles tendon (AT) rupture should immediately be followed by active tendon mobilization. The optimal time as to when the mobilization should begin is important yet controversial. Early kinesitherapy leads to reduced rehabilitation period. However, an insight into the detailed mechanism of this process has not been gained. Proteomic technique can be used to separate and purify the proteins by differential expression profile which is related to the function of different proteins, but research in the area of proteomic analysis of AT 3 days after repair has not been studied so far.</p><p><b>METHODS</b>Forty-seven New Zealand white rabbits were randomized into 3 groups. Group A (immobilization group, n equal to 16) received postoperative cast immobilization; Group B (early motion group, n equal to 16) received early active motion treatments immediately following the repair of AT rupture from tenotomy. Another 15 rabbits served as control group (Group C). The AT samples were prepared 3 days following the microsurgery. The proteins were separated employing two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). PDQuest software version 8.0 was used to identify differentially expressed proteins, followed by peptide mass fingerprint (PMF) and tandem mass spectrum analysis, using the National Center for Biotechnology Information (NCBI) protein database retrieval and then for bioinformatics analysis.</p><p><b>RESULTS</b>A mean of 446.33, 436.33 and 462.67 protein spots on Achilles tendon samples of 13 rabbits in Group A, 14 rabbits in Group B and 13 rabbits in Group C were successfully detected in the 2D-PAGE. There were 40, 36 and 79 unique proteins in Groups A, B and C respectively. Some differentially expressed proteins were enzyme with the gel, matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). We successfully identified 9 and 11 different proteins in Groups A and B, such as GAPDH, phosphoglycerate kinase 1, pro-alpha-1 type 1 collagen, peroxiredoxin 1, alpha-1-antiproteinase E a-1 and MAD2L1 binding protein, etc. And some with the molecular chaperone, oxidative stress, energy metabolism, signal transduction, coupled with the tendon cell expression and protein synthesis, proliferate, differentiate and are closely related to the AT healing. The GAPDH protein was further validated through Western blotting. It was indicated that some differentially expressed proteins were involved in various metabolism pathways and may play an important role in initial healing of AT rupture.</p><p><b>CONCLUSION</b>Differentially expressed proteins in rabbit healing AT model may contribute to 3 days healing of AT rupture through a new mechanobiological mechanism due to the application of postoperative early kinesitherapy.</p>

Proteomic identification and comparison of differentiation-related proteins in gastric carcinoma cell lines / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the differentiation-related proteins in human gastric carcinoma cell lines by comparative proteomics.</p><p><b>METHODS</b>The holoproteins of human gastric carcinoma cell lines MKN28, SGC7901 and BGC823 were measured by two-dimensional gel electrophoresis and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Some proteins identified by proteomics were tested by Western blot in the cell strains and tissues of gastric carcinoma.</p><p><b>RESULTS</b>14 differential protein spots were found in the 3 gastric carcinoma cell lines, among them 8 spots were identified by MALDI-TOF-MS. These proteins were probably thioredoxin peroxidase, glyceraldehyde-3-phosphate dehydrogenase (GAPD), beta-tubulin polypeptide, hypothetical protein, zinc finger protein (ZNF) 139, protein-tyrosine kinase, calreticulin precursor, and tropomyosin, proteins related with biological behavior of gastric carcinoma cells such as signal transduction, cellular homeostasis, glycolysis, antioxidation action, multidrug resistance(MDR), etc. The expressions of those proteins in gastric cancer cells and tissues identified by Western blot were consistent with the results obtained by proteomics.</p><p><b>CONCLUSION</b>Differential proteins are found in 3 human gastric carcinoma cell lines, mainly, proteins related with cell signaling, maintenance of homeostasis, glycolysis, metabolism of anti-cancer drug and anti-oxidative injury, etc.</p>

The relationship between GAPDH mRNA degradation in the mouse liver and postmortem interval / 法医学杂志

OBJECTIVE@#To explore the relationship between degradation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA in the mouse liver and postmortem interval (PMI).@*METHODS@#Sixty NIH mice were sacrificed by cervical dislocation and suffocation, and then placed into 10 degrees C and 25 degrees C temperature-controlling systems. The changes of GAPDH mRNA in the liver were detected by two-step fluorimetric reverse transcriptase polymerase chain reaction (RT-PCR) technique and nucleic acids protein cryoscope from 0 to 48 h postmortem.@*RESULTS@#In the mouse liver, the amplification products of GAPDH mRNA could be examined within 48 h postmortem in 10 degrees C temperature-controlling system and within 36 h postmortem in 25 degrees C temperature-controlling system. The amplification products showed a decreasing tendency.@*CONCLUSION@#Degradation of GAPDH mRNA in the mouse liver is negative correlation with PMI. GAPDH mRNA could be a new marker for estimation of PMI.

The degradation of housekeeping mRNA in dead rats by real-time RT-PCR / 法医学杂志

OBJECTIVE@#To explore the feasibility of real-time RT-PCR of housekeeping mRNA degradation in dead rats in order to seek new suitable techniques for post-mortem interval (PMI).@*METHODS@#The levels of GAPDH mRNA and beta-actin mRNA in the brain and spleen of the rats were measured at different times after death by the SYBR Green I real-time RT-PCR. The relative mRNA level was indicated with the Ct value, then the relationship between the Ct value and PMI were analyzed and the corresponding regression equation was obtained.@*RESULTS@#The Ct values of GAPDH mRNA and beta-actin mRNA by SYBR Green I real time RT-PCR correlated well with the PMI.@*CONCLUSION@#The SYBR Green I real-time RT-PCR is a reliable technique for studying mRNA degradation. Adoption of the housekeeping genes eliminates systematical errors of other genes which have individual difference. As an objective and dynamic indication, Ct value has a good correlation with PMI, and could be applied for estimating PMI, especially in late period.

The prevalence of azoospermia factor microdeletion on the Y chromosome of Chinese infertile men detected by multi-analyte suspension array technology / 亚洲男科学杂志(英文版)

<p><b>AIM</b>To develop a high-throughput multiplex, fast and simple assay to scan azoospermia factor (AZF) region microdeletions on the Y chromosome and establish the prevalence of Y chromosomal microdeletions in Chinese infertile males with azoospermia or oligozoospermia.</p><p><b>METHODS</b>In total, 178 infertile patients with azoospermia (non-obstructed), 134 infertile patients with oligozoospermia as well as 40 fertile man controls were included in the present study. The samples were screened for AZF microdeletion using optimized multi-analyte suspension array (MASA) technology.</p><p><b>RESULTS</b>Of the 312 patients, 36 (11.5%) were found to have deletions in the AZF region. The microdeletion frequency was 14% (25/178) in the azoospermia group and 8.2% (11/134) in the oligospermia group. Among 36 patients with microdeletions, 19 had deletions in the AZFc region, seven had deletions in AZFa and six had deletions in AZFb. In addition, four patients had both AZFb and AZFc deletions. No deletion in the AZF region was found in the 40 fertile controls.</p><p><b>CONCLUSION</b>There is a high prevalence of Y chromosomal microdeletions in Chinese infertile males with azoospermia or oligozoospermia. The MASA technology, which has been established in the present study, provides a sensitive and high-throughput method for detecting the deletion of the Y chromosome. And the results suggest that genetic screening should be advised to infertile men before starting assisted reproductive treatments.</p>

GAPDH activity and immunogenicity of Staphylococcus aureus recombinant GapC protein / 生物工程学报

In order to characterize the Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity, immunogenicity and immunoprotection of the Staphylococcus aureus (S. aureus) surface protein GapC, gapC gene of S. aureus was amplified from strain BMSA/855/23-1 by PCR, and was inserted into pQE-30 vector subsequently. The recombinant plasmid, designated as pQE/gapC, was transformed into E. coli strain M15 (pREP4). The recombinant GapC fusion proein was successfully expressed in E. coli M15 induced with IPTG and its GAPDH activity was confirmed by GAPDH activity assay. Then, the recombinant GapC protein, inactivated S. aureus whole cell and placebo (PBS) were administrated to healthy rabbits respectively. The IgG antibody titers, concentration of IFN-gamma and IL-4 cytokines in immunized rabbit sera were measured with Enzyme-Linked Immunosorbnent Assay (ELISA). Finally, immunized rabbits were challenged with S. aureus strain Wood46 to evaluate the immunoprotection. The IgG antibody titers against GapC and whole cell in rabbit sera reached their peaks at day 28 after boost immunization (1:64,000). The concentration of IL-4 and IFN-gamma in GapC groups rabbit sera increased significantly (P<0.05) at day 14 after boost immunization, while the concentration of those in whole cell group did not increase (P>0.05) compared with the placebo group. 4 rabbits in 5 of the protein immunized group were protected against challenge with 1 x 10(8) CFU S. aureus. The results above indicate that the expressed recombinant GapC protein have high GAPDH activity and immunogenicity, can also protect against S. aureus challenge to some extent. S. aureus GapC protein could be an attractive target for further genetic engineering vaccine.

Expression of mRNAs encoding tumor necrosis factor-alpha and its receptor-I in buffalo ovary.

The tumor necrosis factor-alpha (TNF-alpha) plays an important role in ovarian follicular development and ovulation process and acts through its receptor (TNFRI). The present investigation describes the expression of mRNAs encoding TNF-alpha and TNFRI in relation to glyceraldehyde-3-phosphate dehydrogenase (G3PDH) and beta-actin as control genes, using RT-PCR, in granulosa cells, intact follicles and luteal tissues from buffalo ovary. There was significant higher expression of mRNAs encoding TNF-alpha in granulosa cells from medium follicles and TNFRI expression increased with increase in size of follicles. Post-ovulatory structures (corpus luteum and corpus albicans) exhibited significantly higher expression of TNFRI mRNAs as compared to that obtained in intact follicles suggesting its immediate and critical role just after ovulation, for mediating TNF-alpha action on these tissues. Though the expression of TNF-alpha mRNA was stimulated by treatment of granulosa cells with FSH during culture, the expression of TNFRI mRNA did not change. The FSH alongwith IGF-I did not exert any effect. These results suggested an important role of TNF-alpha and its receptor in buffalo ovarian functions.

Effect of puerarin and daidzein on proliferating vascular smooth muscle cells / 中国中药杂志

<p><b>OBJECTIVE</b>To observe the different effects of Puerarin and Daidzein on the expression of proliferating vascular smooth muscle cells, and to discuss the mechanism.</p><p><b>METHOD</b>MT was used to detect the state of VSMC (vascular smooth muscle cell) activity. The expression levels of Survivin, Bcl-xl, Bax and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) messenger RNA (mRNA) were analyzed quantitatively by reverse transcriptase polymerase chain reaction (Rt-PCR).</p><p><b>RESULT</b>Compared with Puerarin groups, VSMC activity in daidzein groups was lower, and the ratio of Bax/Gapdh/Bcl-xl/Gapdh was higher.</p><p><b>CONCLUSION</b>The inhibition effect of daidzein on VSMC proliferation is stronger than that of puerarin.</p>

Conformational features of a hexapeptide model Ac-TGAAKA-NH2 corresponding to a hydrated alpha helical segment from glyceraldehyde 3-phosphate dehydrogenase: implications for the role of turns in helix folding.

Recent analysis of alpha helices in protein crystal structures, available in literature, revealed hydrated alpha helical segments in which, water molecule breaks open helix 5-->1 hydrogen bond by inserting itself, hydrogen bonds to both C=O and NH groups of helix hydrogen bond without disrupting the helix hydrogen bond, and hydrogen bonds to either C=O or NH of helix hydrogen bond. These hydrated segments display a variety of turn conformations and are thought to be 'folding intermediates' trapped during folding-unfolding of alpha helices. A role for reverse turns is implicated in the folding of alpha helices. We considered a hexapeptide model Ac-1TGAAKA6-NH2 from glyceraldehyde 3-phosphate dehydrogenase, corresponding to a hydrated helical segment to assess its role in helix folding. The sequence is a site for two 'folding intermediates'. The conformational features of the model peptide have been investigated by 1H 2D NMR techniques and quantum mechanical perturbative configuration interaction over localized orbitals (PCILO) method. Theoretical modeling largely correlates with experimental observations. Based upon the amide proton temperature coefficients, the observed d alpha n(i, i + 1), d alpha n(i, i + 2), dnn(i, i + 1), d beta n(i, i + 1) NOEs and the results from theoretical modeling, we conclude that the residues of the peptide sample alpha helical and neck regions of the Ramachandran phi, psi map with reduced conformational entropy and there is a potential for turn conformations at N and C terminal ends of the peptide. The role of reduced conformational entropy and turn potential in helix formation have been discussed. We conclude that the peptide sequence can serve as a 'folding intermediate' in the helix folding of glyceraldehyde 3-phosphate dehydrogenase.

Phosphoglycerate kinase--glyceraldehyde-3-phosphate dehydrogenase interaction: reaction rate studies.

Rate studies using phosphoglycerate kinase (PGK)--glyceraldehyde-3-phosphate dehydrogenase (GPDH) enzyme pair have been carried out to distinguish between the two mechanisms of intermediate metabolite transfer, namely diffusion through the solvent versus "substrate channelling" within an enzyme-enzyme complex. A procedure has been described for the assay of the rates of PGK-catalysed and the PGK-GPDH coupled reactions at high (saturating) GPDH concentration. With PGKs of rabbit muscle and yeast, the coupled reaction proceeded faster than the PGK-catalysed reaction. At a high salt concentration (0.5 M KCl), where a PGK-GPDH complex is known to dissociate, the two reactions proceeded at almost equal rates. At fixed PGK concentration, the rate of the coupled reaction at high (saturating) GPDH concentration varied with the nature (biological origin) of the latter enzyme. In the presence of 0.5 M KCl, the saturating rate values with different GPDHs were almost equal. The PGK-catalysed reaction exhibited typical Michaelian behaviour on varying the substrate concentrations (linear double reciprocal plots). The Km values for 3-PGA (0.51 mM) and ATP (0.40 mM) were independent of the concentration of the second substrate. The double reciprocal plots for the coupled reaction showed downward curvature, i.e. activation at higher substrate concentrations. The ratio of the rate of the coupled reaction: the rate of the PGK catalysed reaction was found to be a function of the nature of PGK, nature of GPDH, nature of buffer, pH, salt concentration and substrate concentrations. The ratio varied between close to unity at low substrate concentrations, to three when the Vmax values of the two reactions were compared. At low substrate concentrations, the rate of the coupled reaction became independent of the nature of GPDH. It has been suggested that in the PGK-GPDH pair, the intermediate metabolite (BPG) is transferred directly from one enzyme to the other within an enzyme-enzyme complex, except at high salt or low substrate concentrations. Under the latter conditions, data were consistent with metabolite transfer by diffusion. Implications of these results for coupled enzyme assays have been discussed.

Acción de las hormonas tiroideas sobre la modulación de la expresión genética de la enzima málica citosólica hepática, en ratas intoxicadas con hexaclorobenceno / Action of the thyroid hormone on modulation of the gene expression of the liver cytosolic malic enzyme, in intoxicated rats with hexachlorobenzene

El hexaclorobenceno (HCB) es un tóxico ampliamente distribuído en la biosfera. La exposición crónica de animales de laboratorio al HCB provoca disfunciones tiroideas. Previamente hemos demostrado que el HCB incrementa la actividad de enzimas hepáticas reguladas por hormonas tiroideas (HT) tales como: enzima málica (EM) y glucosa-6fosfato de dehidrogenasa (G6PD) sin alterar la actividad de la alpha-glicerol fosfato deshidrogenasa mitocondrial (alpha-GPD). En éste estudio hemos investigado si el HCB afectaba: a) la concentración del receptor de hormonas tiroideas (RT3) y su afinidad por el ligando, b) la expresión del gen de EM y de otras enzimas HT-dependientes, c) los complejos proteína/DNA formados sobre el elemento de respuesta a hormonas tiroideas (TRE). Se utilizaron hígados de ratas hembras Wistar intoxicadas con HCB (100 mg/100 g P.C.), por 9 y 15 días. El análisis de Scatchard mostró que ni la afinidad ni el número de sitios RT3 estaban alterados luego de 9 y 15 días de tratamiento con HCB (Control, Ka: 1,9 nM, Bmáx:3.9 fmol/100mug DNA; HCB9díasKa2.1nM, Bmáx4.5 fmol/100mug DNA; HCB15 días Ka 1.9nM, Bmáx5.1 fmol/100mug DNA). Tampoco los niveles de RNAm de TRbeta1 medidos por ensayos de protección a RNasa fueron afectados por HCB. Ensayos de Northern Blot han demostrado que los niveles de RNAm de EM se incrementaban 4 veces y 2 veces con respecto al control después de 9 y 15 días de intoxicación respectivamente, sin observarse alteraciones en los niveles de RNAm de otras enzimas cuya expresión es regulada por HT como gliceraldehído - 3 - fosfato deshidrogenasa (GAPDH) y fosfoenolpiruvatocarboxiquinasa (PEPCK) ni tampoco en la alpha-GPD mitocondrial. Ensayos de retardo en gel mostraron que el HCB no modificó la afinidad de las proteínas presentes en extractos nucleares por el TRE presente en el promotor de EM. Nuestros resultados sugieren que el RT3 no está involucrado en forma directa en la inducción de la expresión del gen de EM por HCB, sin embargo podría interaccionar con otros factores de transcripción en la sobreexpresión del gen de EM.