TFG regulates inner COPII coat recruitment to facilitate anterograde secretory protein transport.

Coat protein complex II (COPII) governs the initial steps of biosynthetic secretory protein transport from the endoplasmic reticulum (ER), facilitating the movement of a wide variety of cargoes. Here, we demonstrate that Trk-fused gene (TFG) regulates the rate at which inner COPII coat proteins are concentrated at ER subdomains. Specifically, in cells lacking TFG, the GTPase-activating protein (GAP) Sec23 accumulates more rapidly at budding sites on the ER as compared to control cells, potentially altering the normal timing of GTP hydrolysis on Sar1. Under these conditions, anterograde trafficking of several secretory cargoes is delayed, irrespective of their predicted size. We propose that TFG controls the local, freely available pool of Sec23 during COPII coat formation and limits its capacity to prematurely destabilize COPII complexes on the ER. This function of TFG enables it to act akin to a rheostat, promoting the ordered recruitment of Sec23, which is critical for efficient secretory cargo export.

Purification of enramycin by macroporous resin adsorption and reversed phase chromatography purification / 生物工程学报

Enramycin is a polypeptide antibiotic and new, safe animal feed additive. A new purification process was developed, based on pre-purification by macroporous resin and refining by reversed phase chromatography. AB-8 macroporous resin was used for the pre-purification process of enramycin, with an elution buffer of 0.012 mol/L aqueous HCl solution-methanol (50: 50, V/V). Then, enramycin a and enramycin b were separated effectively by C18 reversed phase chromatography, with a elution buffer of 0.05 mol/L aqueous KH2PO4 solution-acetonitrile (70: 30, V/V, pH 4.5). The purities of enramycin a and enramycin b were up to 98.5% and 98.0%, respectively. The yield reached 29.2%. This study would provide a useful reference for the preparation of enramycin a and enramycin b with a high purity.

[Study on malignant and normal rectum tissues using IR and 1H and 31P NMR spectroscopy].

In the present paper, NMR spectroscopy, an effective tool to detect the variation in, molecular structure and changes in chemical composition of metabolites in tissues, was used to study the differences between malignant and normal tissues from rectum. 1H and 31P spectra of seven malignant rectum tissue samples and five normal control tissues were investigated by using a 300 M NMR spectrometers and compared with the results of the infrared spectra of normal and malignant rectum organ tissues. The results indicate that the 1H and 31P spectra of rectum cancer tissues are significantly different from those of the normal controls and most differences present in the form of variation in relative intensities of the characteristic peaks of various metabolites. Systematic differences in the NMR spectra between malignant tissues and normal controls are as follows: in the 1H NMR spectra, differences lie in fatty acids with the concentration of fatty acid decreasing significantly in malignant tissues. In the 31P NMR spectra, differences lie in phospholipid, with the chemical shift of phospholipid decreasing significantly in malignant tissues. This phenomenon may reflect the fact that the activity of protein synthesis is enhanced in cancerous tissues. The difference in the chemical shift of phospholipid between normal rectal tissue and malignant tissue may be considered as a detection criterion. Therefore, the above spectral variations in 31P NMR spectra may be utilized as a potential tool to diagnose rectum cancer.

[Study of malignant and normal tissues of the rectum using NMR spectroscopy].

In the present paper, NMR spectroscopy, an effective tool to detect the variation in molecular structure and changes in chemical composition of metabolites in tissues, was used to study the differences between malignant and normal tissues from rectum. 1H spectra of four malignant rectum tissue samples and two normal control tissues were investigated by using a 500M NMR high-resolution magic angle spinning magnetic resonance spectrometers (HR-MAS NMR). The results indicate that the 1H HR-MAS spectra of rectum cancer tissues are significantly different from those of the normal controls and most differences are presents in the form of variation in the relative intensities of the characteristic peak of various metabolites. In order to characterize the variation in the relative intensities in a quantitative manner, the intensity of the methyl peak of fatty acid at 0.88 was utilized as inner standard. Systematic differences between NMR spectra of malignant tissue and normal controls are as follows: (1) The concentration of amino acid increases significantly in malignant tissues, since the relative intensities of characteristic peaks of amino acid including valine, isoleucine, leucine, lysine, glutamate, glutamine, and aspartate are stronger in the NMR spectra of the malignant tissues. This phenomenon may reflect the fact that the activity of protein synthesis is enhanced in cancerous tissues. (2) The intensities of the characteristic peaks of lactic acid in malignant tissues are higher than those from normal controls. This may be related to the nature of anaerobic metabolism activity in malignant tissues. (3) The level of choline and its derivatives, taurine and creatine, increases significantly in malignant tissues, suggesting that the metabolic activity of malignant tissues changes. (4) In the spectral region between 4.5 and 10, observable changes occur on the peaks for unsaturated fatty acid and nuclear acids. Therefore, the above spectral variations in high resolution magic angle spinning NMR spectroscopy may be utilized as a potential tool to diagnose rectum cancer.

[Progress in nuclear magnetic resonance spectroscopy for early cancer diagnosis].

Based on more than 100 references, the present paper reviews the progress in the application of nuclear magnetic resonance (NMR) spectroscopy, an effective method to study the variation in chemical composition and molecular structure in biological samples for early diagnosis of cancer at molecular level. In the past several decades, numerous works have demonstrated that NMR spectroscopy may be developed into a sensitive diagnosis method to detect cancer in early stage. Because of the rapid development of NMR spectroscopic techniques, it becomes possible to record NMR spectra of biological samples in both in-vitro and in-vivo manner. Systematic spectral differences between biological samples from cancer patients and normal controls can be observed from both liquid-state and solid-state 1H, 31P NMR spectra and used to reflect the changes in metabolic behavior of malignant tissues. This paper has summarized NMR spectroscopic investigation on biological fluid, cultured cancerous cells, resected tissues, as well as in-vivo malignant tissues by using various advanced NMR techniques including recently developedhigh-resolution magic angle spinning (HR-MAS)and magnetic resonance spectroscopy and imaging (MRSI) methods. First, characteristic peaks, which are related to choline, phosphocholine (PC) and glycerophosphocholine, can be observed in both 1H and 31P NMR spectra of biological fluid samples from cancer patients. These results indicate that alternation in the metabolic pattern occurs with the progression of cancer. The research on cultured cells by using NMR spectroscopy showed that the signal of various phospholipids and their metabolites such as PME increased significantly in cultured cancer cells. For resected tissues, two methods can be utilized. The first one is to investigate the tissues directly by using HR-MAS spectroscopy. The second method is to extract various metabolites with various solvents such as CHCl3/methonal mixtures, HClO4 solutions, etc. and then analysis of the extracted solutions is performed using conventional liquid NMR spectroscopy. Significant differences on the content of various amino acids, metabolites of phospholipids, can be observed between malignant tissues and normal controls in NMR spectra. Recently, MRSI that can acquire 1H-NMR spectra of suspected tissues during the process of MRI diagnosis is available. The approach makes it possible for the surgeons to judge whether the suspected tissues are malignant or not before surgical operation. The above results demonstrate that NMR spectroscopy possesses bright perspective in diagnosing cancers and differentiating different types of cancers based on the metabolic behavior of cancerous tissues.

[A study on the NMR spectrum of methyl-ofloxacin].

Ofloxacin ((+/-)-9-fluoro-3-methyl-10-(4-methylpiperazin-1-yl)-7-oxo-2, 3-dihydro-7H-pyrido[1,2,3-de]-1, 4-benzoxazine-6-carboxylic acid) is a totally synthetic fluoroquinolone antimicrobial agent with a broad spectrum of activity against Gram-positive and Gram-negative bacteria and atypical pathogens such as Mycoplasma, Chlamydia and Legionella. Even though it is widely used for the treatment of gastrointestinal, pulmonary, urinary, and other infections, the comprehensive mechanism of action at molecular level has not been known so far. It is very important to understand the structural characteristics of the drug and the effects that are caused by the environments. With the purpose of deeply investigating the structure of Ofloxacin, an analog of Ofloxacin, Methyl-Ofloxacin (Me-OFL), was synthesized by methylation of 4'N in piperazine ring from Ofloxacin with CH3I. Then appropriate Me-OFL was dissolved in DC1/D2O and NaOH/D2O to prepare corresponding acidic and alkaline solutions. Systematic NMR spectroscopic investigation on Me-OFL in both acidic and alkaline solution was conducted using quantitative 1H and 13C spectra, DEPT, HSQC together with HMBC techniques. The spectra were recorded with Bruker AM-300 spectrometer and DRX500 spectrometer. Chemical shifts have been given in values referred to dioxane (deltaJ = 3.7, deltac = 67.8). Complete assignments on 1H and 13C signals of Me-OFL were obtained in different pH environments where the coupling constant between 13 C and 19F was found to be very helpful for the assignment of aromatic 13C signals. A comprehensive comparison between the 1H, 13C chemical shifts, together with the structural transformation in acidic and alkaline solutions was made and discussed in details. Due to the formation of hydrogen bond between COOH and C==O, the COOH and aromatic ring are in the same plane. As a result, a weak O...H--C hydrogen bond forms between C==O from the carboxyl group and 5-H from aromatic ring. In alkaline solution, the deprivation of H+ from COOH destroys not only the hydrogen bond between COOH and carbonyl group but also the weak hydrogen between the C==O from COOH and 5H. As a result, the 5H exhibited remarkable shift toward high field (1.02). Meanwhile, the chemical shift of 6C, 13C, 7C, 15C also exhibited remarkable shift to low field at 12. 04, 7.46, 4.33, 2.88 respectively. Such variations were related to the changes of p electrons from carboxyl group caused by the transformation between the carboxyl group and the carboxylate group in different pH environments. Comparison of deltaH, deltac data between Me-OFL and OFL in acidic solution and OFL in alkaline was made. In Me-OFL acidic solution, the chemical shift of 3'C, 5'C, 7'C, 8'C also exhibited remarkable shift to low field at 6.66-7.32 respectively, the chemical shift of 2'C and 6'C also exhibited remarkable shift to high field 6.04. In OFL acidic solution, the chemical shift of 2'C, 3'C, 5'C, 6'C, 7'C, 8'C also exhibited remarkable shift to high field within 2.39, Comparison between the protonation and the methylation on the 4'N atom from the piperazine ring was also made. The distribution of positive charge also showed difference. When protonation occurred on the piperazine ring, the positive charge was on the proton connected with 4'N. However, if methylation occurred, the positive charge is on the 4'-N atom.

[Study on the malignant and normal rectum tissues using 1H NMR spectroscopy].

Cancer is one of the most serious diseases, a threat to human body's health and a causes of death. The early diagnosis of cancer and timely therapy is significant for improving the survival. Owing to the complexity and limit of conventional medical diagnosis, misdiagnosis of ten occurs in many cases. NMR spectroscopy is an effective technique for characterizing molecular structure and component changes. The component and structural information of nucleic acid, protein, lipid and glucide in the biologic tissues can also be distinguished from NMR data. In the present paper, a new method was developed for the diagnosis of tumor using the advanced physical chemistry (NMR) and biomedicine technique. Nine rectum tissue samples and their corresponding normal tissues of rectum were measured using NMR spectroscopy. Each tissue sample obtained from the operation was quickly separated into two parts averagely: one was dipped into 10% formalin solution and prepared for conventional pathological examination; the other was preserved in liquid nitrogen for further NMR detection. Before NMR detection, the corresponding sample was thawed at room temperature and was dipped into 0.5 mL D2O. Dioxane was used as external reference. The obtained NMR spectra were analyzed and compared by OMNIC5.0 and SPSS 11.0 Software. The differences of metabolite in the tissues samples were studied and a method for the diagnosis of cancer using NMR data was initially explored. The result indicates that the 1H NMR spectra of rectum cancer tissues are significantly different from those of their corresponding normal rectum tissues. This is shown by the differences in the integral area ratio at characteristic peak region. A0.9/A3.0, A1.3/A3.0, A2.0/ A3.0, A1.3/A0.9 and A4.1/A3.0 of the normal rectum tissues are higher than those of their corresponding cancer tissues, but A3.2/A3.0 is lower than that of the rectum cancer tissues. From the above result it is concluded that the concentration of fatty acid, inositol and lactate is lower in the rectum cancer tissues than in the normal tissues, while that of choline bases compounds is higher. The NMR judgments were also consistent with the pathological examination results. So the NMR spectra may be developed into a method of early diagnosing rectum cancer through these differences.