The hydration reaction by microbial method is the crisis of the procedure of acrylamide production from acrylonitrile. This research studied the enzyme catalytic kinetics and de-active kinetics of nitrile hydratase in the type of free cell. Firstly, the effects of the concentration of cells, the temperature, pH value, the concentration of acrylonitrile and the concentration of acrylamide on the activity of nitrile hydratase was investigated. The result is that the temperature and the concentration of acrylamide are the most important among these factors. The activity of the nitrile hydratase was 5659 u/mL (broth) at 28 degrees C; the counterpart was only 663 u/mL (broth) at 5 degrees C. And the activity of NHase in solution of 45% acrylamide was just about half of that in solution of 5% acrylamide. After study on the relation of temperature and the reaction speed, It was found that the activation energy of the hydration of NHase was 65.57 kJ.mol-1. This paper studied the effects of concentration of cells, temperature, pH value, concentrations of acrylonitrile and acrylamide on the deactivation of Nhase, as well as the related enzyme de-active kinetics. The result also showed that the temperature and the concentration of acrylamide are the most important among these factors. In solution of 35% acrylamide, the residual activity was about 0% of the original value after 55 h; but in solution of 10% acrylamide, after the same period of time, the residual activity was 50% of the original one. It was also found that the concentration of acrylonitrile had little effect on the stability of NHase. The coefficient of deactivation at 28 degrees C was 21.77 times of the one at 5 degrees C. Correlating the temperature and the coefficient of deactivation, the activation energy of the de-active reaction was found to be 92.28 kJ.mol-1.
Acrylamide ; metabolism ; Acrylonitrile ; metabolism ; Catalysis ; Hydro-Lyases ; metabolism ; Hydrogen-Ion Concentration ; Kinetics ; Rhodococcus ; enzymology ; Temperature

Nitriles are an important type of synthetic intermediates in the production of fine chemicals because of their easy preparations and versatile transformations. The traditional chemical conversion of nitriles to carboxylic acids and amides is feasible but it requires relatively harsh conditions of heat, acid or alkali. Nitrile converting enzymes (nitrilase, nitrile hydratase and amidase) which are used as biocatalyst for the production of fine chemicals have attracted substantial interest because of their ability to convert readily available nitriles into the corresponding higher value amides or acids under mild conditions with excellent chemo-, regio- and stereo-selectivities. Many nitrile converting enzymes have been explored and widely used for the production of fine chemicals. In this paper, various examples of biocatalytic synthesis of pharmaceuticals and their intermediates, agrochemicals and their intermediates, food and feed additives, and other fine chemicals are presented. In the near future, an increasing number of novel nitrile converting enzymes will be screened and their potential in the production of useful fine chemicals will be further exploited.
Amides ; metabolism ; Amidohydrolases ; metabolism ; Aminohydrolases ; metabolism ; Carboxylic Acids ; metabolism ; Chemical Industry ; methods ; Hydro-Lyases ; metabolism ; Nitriles ; chemistry

OBJECTIVETo study the effect of astrocyte exosomes on hypoxic-ischemic neurons.

METHODSRat astrocytes were cultured in vitro, and differential centrifugation was used to obtain the exosomes from the cell supernatant. Transmission electron microscopy, Nanosight, and Western blot were used for the identification of exosomes. BCA method was used to measure the concentration of exosomes. Rat neurons were cultured in vitro and then divided into control group, exosome group, oxygen glucose deprivation (OGD) group, and OGD+exosome group (n=3 each). The OGD and OGD+exosome groups were cultured in glucose-free medium under the hypoxic condition. The exosome and OGD+exosome groups were treated with exosomes at a final concentration of 22 μg/mL. The control and OGD groups were given an equal volume of phosphate-buffered saline. ELISA was used to measure the level of lactate dehydrogenase (LDH) in neurons. The terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling was used to measure the apoptotic index of neurons.

RESULTSThe identification of exosomes showed that the exosomes extracted by differential centrifugation had the features of exosomes. Compared with the control and exosome groups, the OGD group had significant increases in LDH level and apoptotic index (P<0.05). Compared with the OGD group, the OGD+exosome group had significant reductions in LDH level and apoptotic index (P<0.05).

CONCLUSIONSThe exosomes from astrocytes have a protective effect on neurons with hypoxic-ischemic injury.

Animals ; Apoptosis ; Astrocytes ; physiology ; Cell Hypoxia ; Cells, Cultured ; Exosomes ; physiology ; Glucose ; deficiency ; Hydro-Lyases ; analysis ; Neuroprotection ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the alteration of the gene HSD17B4 in esophageal squamous cell carcinoma and its potential significance.

METHODSThe mRNA expression and loss of heterozygosity (LOH) of HSD17B4 in 40 primary esophageal tumors were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and microsatellite analysis with the intragenic marker D5S1384 of the gene.

RESULTSThe frequencies of allelic loss of D5S1384 and the rate of down-regulation of gene HSD17B4 were 46.2% and 62.5%, respectively.

CONCLUSIONHSD17B4 may be a candidate tumor suppressor gene associated with esophageal squamous cell carcinoma.

17-Hydroxysteroid Dehydrogenases ; biosynthesis ; genetics ; Adult ; Aged ; Carcinoma, Squamous Cell ; genetics ; Down-Regulation ; Enoyl-CoA Hydratase ; biosynthesis ; genetics ; Esophageal Neoplasms ; genetics ; Female ; Gene Expression ; Gene Expression Regulation, Neoplastic ; genetics ; Genes, Tumor Suppressor ; Humans ; Hydro-Lyases ; Loss of Heterozygosity ; Male ; Microsatellite Repeats ; Middle Aged ; Multienzyme Complexes ; biosynthesis ; genetics ; Peroxisomal Multifunctional Protein-2 ; RNA, Messenger ; biosynthesis ; genetics ; Reverse Transcriptase Polymerase Chain Reaction

PURPOSE: The histiogenesis of retinoblastoma, the most common intraocular malignancy of childhood, has been investigated from the early times. But in spite of this effort, its origin has been controversial. This study was performed to investigated the cell of origin for retinoblastoma using enzyme histomchemistry for carbonic anhydrase. METHODS: We obtained enucleated eye that was diagnosed as retinoblastoma and its section was stained for hematoxylin-eosin for diagnosis of retinoblastoma. We used enzyme histomchemistry for carbonic anhydrase distinguishing Muller's cells, red-and green-sensistive cones from neuro-retinal cells. RESULTS: They were disagnosed as relatively well-differentiated retinoblastoma by hematoxylin-eosin staining and composed of tumor cells with numerous rosette. Neither numeric nor morphologic changes of Muller cells that are suspected of malignant features in enzyme histochemistry for carbonic anhydrase was found. CONCLUSIONS: The cells of retinoblastoma were originated from the two layers, inner nuclear and ganglion cell layer. The enzyme histochemistry for carbonic anhydrase is the one of the useful methods to investigate the origin of retinoblastoma although more cases is needed to assess.
Carbonic Anhydrase I ; Carbonic Anhydrases ; Diagnosis ; Ependymoglial Cells ; Ganglion Cysts ; Retinoblastoma*

To test the hypothesis that in vitro protein cross-linking could be accomplished in three concerted steps: (1) a change in protein conformation; (2) formation of interchain disulfide bonds; and (3) formation of interchain isopeptide cross-links, we amplified wild and Cys/Ser mutant genes with PCR technique from E. coli BL21 cells and subcloned them into expression plasmid pTrcHisC. Recombinant proteins, which were associated with formation of inclusion bodies induced by IPTG, were purified by immobilized metal affinity chromatography (IMAC) and refolded by dialysis. In thermal unfolding and oxidative refolding experiment, wild TtdB was proved to form cross-linked dimmers/oligomers as revealed by SDS-PAGE; cross-linking intensity was obviously weakened when the loading buffer contained the reducing agent dithiothreitol (DTT). The residual cross-linking was isopeptide bonds; no dimmers/oligomers were detected when the refolding and unfolding solution contained DTT. In addition, Cys/Ser point mutation abrogated its ability to cross-link into homodimers, which showed disulfide bonds could facilitate the following formation of isopeptide bonds.
Cross-Linking Reagents ; chemistry ; Escherichia coli ; enzymology ; genetics ; Escherichia coli Proteins ; chemistry ; Hydro-Lyases ; chemistry ; genetics ; Mutation ; Protein Disulfide-Isomerases ; chemistry ; Protein Folding

The cultural conditions for the growth of Norcardia cell were studied in this paper. Controlling pH value, adding nutrient and optimizing the quantity of inducer during cultivation, the activity of nitrile hydratase reached 6567 u/mL (culture medium), which was the highest value appeared in native journals. In the farther hydratase experiments, no by-product, crylic acid, was detected. It showed that the activity of amidase was not promoted obviously while the activity of nitrile hydratase was increased greatly. The results set a strong foundation for the industrial application and the research on new technology.
Acrylamides ; metabolism ; Amidohydrolases ; metabolism ; Biotechnology ; methods ; Cell Culture Techniques ; Fermentation ; physiology ; Glucose ; metabolism ; Hydro-Lyases ; metabolism ; Hydrogen-Ion Concentration ; Nocardiaceae ; enzymology ; metabolism

There is growing interest in biodiesel and this results in the accumulation of glycerol. The exploitation and application of glycerol has attracted more and more attention. In the current study, glycerol was biotransformed to produce 3-hydroxypropionaldehyde by genetic engineering bacteria. It is known that 3-hydroxypopionaldehyde has been widely used as an important intermediate for chemicals, effective antimicrobial agent, and fix agent for tissues. A pair of primers was designed on the basis of the sequence of both NH2-terminus and the amino acid sequence of glycerol dehydratase reported by NCBI, and a fragment about 1.6 kb was obtained by PCR amplification using the total genome DNA of Lactobacillus reuteri as template, then the fragment was cloned to the pMD18-T vector and sequenced. Two specific primers were designed according to the obtained sequence, and a fragment with length of 1674 bp was amplified using PCR with these two specific primers. Consequently, the resulting products were digested with EcoR I and Hind III and ligated using T4 DNA ligase to the pET28b vector digested with the same enzymes. The recombinant plasmid, named pET28b-dhaB, was transformed into E. coli BL21. The positive clones were induced with IPTG and the expression products were further analyzed by SDS-PAGE, indicating that protein with a molecule weight of around 65 kD was obtained. Furthermore, the glycerol dehydratase activity was evaluated and compared with the wild type strain as well.
Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Glyceraldehyde ; analogs & derivatives ; chemistry ; metabolism ; Hydro-Lyases ; biosynthesis ; genetics ; Lactobacillus reuteri ; enzymology ; genetics ; Propane ; chemistry ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics

The dhaB gene encoding glycerol dehydratase and dhaG dhaF gene encoding glycerol dehydratase reactivating factor from Citrobacterfreundii were amplified by PCR. The temperature control expression vector pHsh harboring yqhD, dhaB, dhaG and dhaF gene was transformed into E. coli JM109 to yield the recombinant strain E. coli JM109 (pHsh-dhaB-dhaG-dhaF-yqhD). The results from SDS-PAGE analysis show that the recombinant product was consistent with the molecular weight predicted from gene sequence. The fermentation result show that the yield of 1,3-propanediol was increased by 28% compared with E. coli JM109(pHsh-dhaB-yqhD).
Bacterial Proteins ; biosynthesis ; genetics ; Citrobacter freundii ; genetics ; metabolism ; Escherichia coli ; genetics ; metabolism ; Hydro-Lyases ; biosynthesis ; genetics ; Propylene Glycols ; metabolism ; Transformation, Bacterial ; genetics

OBJECTIVETo observe the effect of transplantation of allogeneic adipose-derived stem cells (ADSCs) on serum biochemical indicators and sporting ability in highly endurance-trained rats from a fasciological perspective.

METHODSThe ADSCs were cultured in vitro. Forty male Wistar rats were randomized into 4 equal groups, namely the blank control group, overtraining (model) group, transplantation without training group and overtraining plus transplantation group. The rats in the two overtraining groups were subjected to exhaustive swimming for 1 week, and in the two transplantation groups, cultured allogeneic ADSCs (2×10(6)/ml) were injected via the tail vein. The exhaustion time in swimming and the serum levels of BUN, LDH, BLa, and Hb of the rats were recorded after the treatments.

RESULTSThe rats in the model group showed significantly increased serum BUN, LDH and BLa levels and decreased Hb level with a extended exhaustion time as compared with those in the blank control group (P<0.01). The BUN, LDH and BLa was significantly lower, Hb level higher and the exhaustion time significantly longer in the overtraining plus transplantation group than those in the model group (P<0.01).

CONCLUSIONSADSCs can effectively prolong the exhaustion time of rats during exhaustive swimming and enhance their sporting ability.

Adipose Tissue ; cytology ; Animals ; Blood Urea Nitrogen ; Fatigue ; prevention & control ; Hydro-Lyases ; blood ; Lactic Acid ; blood ; Male ; Physical Conditioning, Animal ; physiology ; Physical Exertion ; physiology ; Rats ; Rats, Wistar ; Stem Cell Transplantation ; methods ; Swimming