Seven virulent bacteriophages of Streptococcus thermophilus were characterized at the molecular level and classified into 2 subgroups (A and B) by DNA/DNA hybridization experiments and analysis of their structural proteins. Two representatives of subgroups A and B were compared to 3 representatives of Neve's subgroups I, II and III (Neve et al, 1989) by Southern blot experiments. These isometric-headed phages possess a double-stranded DNA genome varying between 30-44 kilobase (kb) pairs. Subgroup A is composed of 3 phages (phi 57 as representative) with similar structural proteins as determined by sodium dodecyl sulfate-poly-acrylamide gel (SDS-PAGE) electrophoresis (estimated molecular weights of 31,000 and 27,500 for phage phi 57 and 32,000 and 27,000 for the 2 others). A common structural protein of 43,000 was found for phages of subgroup B. Phages phi 57 (subgroup A) and a10/J9 or PO (Neve's subgroups I or II, respectively) belonged to the same subgroup as determined by DNA/DNA hybridization experiments. Partial DNA homology was detected among all the phages tested except for phage phi ST27 of AW Jarvis. Phage-host interactions were also investigated by cross-propagation of the 7 studied phages on different indicator strains. A complete lack of correlation existed between the DNA homology grouping of the phages and their host range. Various restriction-modification systems were detected in some of the Streptococcus thermophilus strains. 相似文献
Antibody-drug conjugates are now of considerable interest and are recommended for the treatment of cancers. Linkers are having a crucial role in potency and efficacy of these drugs. Herein, for the first time, we have used a water-soluble poly-ethylene glycol based linker (succinimidyl-[(N-maleimido propionamido)-diethyleneglycol] [SM(PEG)2]) for lysine amide coupling of DM1 drug to trastuzumab considering evaluation of the effect of using a hydrophilic linker on physicochemical and biological properties of the resulting conjugate in comparison to the conjugate containing succinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC) linker, which has a relative hydrophobic nature. The physicochemical properties of synthesized conjugates were investigated in terms of drug to antibody ratio, size variants and free drug quantities. In vitro biological activity of trastuzumab-DM1 conjugates was assessed on breast cancer cell lines expressing different levels of HER2 using binding affinity, antiproliferative, apoptosis, and antibody-dependent cell-mediated cytotoxicity (ADCC) assays. Synthesized conjugate containing hydrophilic linker, showed higher drug to antibody ratio, no aggregated form and higher cellular toxicity in comparison to SMCC bearing conjugate. Binding affinity and ADCC potential of conjugates was not affected upon the usage of hydrophilic linker. In conclusion, application of SM(PEG)2 for coupling of DM1 to trastuzumab enhance desirable characteristics of the resulting conjugate. 相似文献
A mass spectrometric analysis of proteins partitioning into Triton X-114 from purified hepatic Golgi apparatus (84% purity by morphometry, 122-fold enrichment over the homogenate for the Golgi marker galactosyl transferase) led to the unambiguous identification of 81 proteins including a novel Golgi-associated protein of 34 kDa (GPP34). The membrane protein complement was resolved by SDS-polyacrylamide gel electrophoresis and subjected to a hierarchical approach using delayed extraction matrix-assisted laser desorption ionization mass spectrometry characterization by peptide mass fingerprinting, tandem mass spectrometry to generate sequence tags, and Edman sequencing of proteins. Major membrane proteins corresponded to known Golgi residents, a Golgi lectin, anterograde cargo, and an abundance of trafficking proteins including KDEL receptors, p24 family members, SNAREs, Rabs, a single ARF-guanine nucleotide exchange factor, and two SCAMPs. Analytical fractionation and gold immunolabeling of proteins in the purified Golgi fraction were used to assess the intra-Golgi and total cellular distribution of GPP34, two SNAREs, SCAMPs, and the trafficking proteins GBF1, BAP31, and alpha(2)P24 identified by the proteomics approach as well as the endoplasmic reticulum contaminant calnexin. Although GPP34 has never previously been identified as a protein, the localization of GPP34 to the Golgi complex, the conservation of GPP34 from yeast to humans, and the cytosolically exposed location of GPP34 predict a role for a novel coat protein in Golgi trafficking. 相似文献
Clinical guidelines recommend that violence risk be assessed in schizophrenia. Current approaches are resource-intensive as they employ detailed clinical assessments of dangerousness for most patients. An alternative approach would be to first screen out patients at very low risk of future violence prior to more costly and time-consuming assessments. In order to implement such a stepped strategy, we developed a simple tool to screen out individuals with schizophrenia at very low risk of violent offending. We merged high quality Swedish national registers containing information on psychiatric diagnoses, socio-demographic factors, and violent crime. A cohort of 13,806 individuals with hospital discharge diagnoses of schizophrenia was identified and followed for up to 33 years for violent crime. Cox regression was used to determine risk factors for violent crime and construct the screening tool, the predictive validity of which was measured using four outcome statistics. The instrument was calibrated on 6,903 participants and cross-validated using three independent replication samples of 2,301 participants each. Regression analyses resulted in a tool composed of five items: male sex, previous criminal conviction, young age at assessment, comorbid alcohol abuse, and comorbid drug abuse. At 5 years after discharge, the instrument had a negative predictive value of 0.99 (95% CI = 0.98–0.99), meaning that very few individuals who the tool screened out (n = 2,359 out of original sample of 6,903) were subsequently convicted of a violent offence. Screening out patients who are at very low risk of violence prior to more detailed clinical assessment may assist the risk assessment process in schizophrenia. 相似文献
Discovered in 1909 by Retzius and described mainly by morphology, the cytoplasmic droplet of sperm (renamed here the Hermes body) is conserved among all mammalian species but largely undefined at the molecular level. Tandem mass spectrometry of the isolated Hermes body from rat epididymal sperm characterized 1511 proteins, 43 of which were localized to the structure in situ by light microscopy and two by quantitative electron microscopy localization. Glucose transporter 3 (GLUT-3) glycolytic enzymes, selected membrane traffic and cytoskeletal proteins were highly abundant and concentrated in the Hermes body. By electron microscope gold antibody labelling, the Golgi trafficking protein TMED7/p27 localized to unstacked flattened cisternae of the Hermes body, as did GLUT-3, the most abundant protein. Its biogenesis was deduced through the mapping of protein expression for all 43 proteins during male germ cell differentiation in the testis. It is at the terminal step 19 of spermiogenesis that the 43 characteristic proteins accumulated in the nascent Hermes body. 相似文献
Many methodologies have been established to lessen negative impacts of salinity on plants. Of those methodologies, nanoparticles (NPs) application has achieved great importance thanks to their unique physico-chemical properties. Consequently, formerly respecting encouraging impacts of graphene oxide (GO) and proline (Pro) on different plant processes under non-stress and stress conditions, proline-functionalized graphene oxide nanoparticles “GO–Pro NPs” were synthesized and characterized. Graphite powder, as starting material, was used to synthesize GO using modified Hummers method followed by functionalization of its surface by proline in basic media. Afterward, GO–Pro NPs, GO and Pro, each at 0, 50 and 100 mg L?1 concentrations with three replications, were applied on Moldavian balm (Dracocephalum moldavica L.) plants to assay their effects under non-stress (0 mM) and salt stress (50 and 100 mM) conditions. GO–Pro NPs and Pro effectively alleviated negative effects of salinity through increasing morphological parameters, photosynthetic pigments, chlorophyll fluorescence parameters, chlorophyll index (SPAD), and membrane stability index (MSI) and decreasing hydrogen peroxide and malondialdehyde, as well. Also application of GO–Pro NPs enhanced proline, antioxidant enzymes activities, and most dominant constituents of essential oil. The highest MSI (48.87%) and proline content (15.36 µM g?1 FW) were observed in plant treated with GO–Pro NPs (50 mg L?1) under 100 mM NaCl salinity stress. The GO–Pro NPs treatment at lower dose (50 mg L?1) could be introduced as the best preservative treatment for Moldavian balm under salt stress. GO application mostly had no effect on the measured parameters announcing it as carrier for Pro to enhance its efficiency. In conclusion, GO–Pro NPs application could promote Moldavian balm performance and essential oil under salinity presenting GO–Pro NPs as new treatment against stress conditions.
Diethylenetriamine pentaacetic acid (DTPA) is a popular chelator agent for enabling the labeling of peptides for their use in structure-activity relationship study and biodistribution analysis. Solid phase peptide synthesis was employed to couple this commercially available chelator at the N-terminus of either the A-chain or B-chain of H2 relaxin. The coupling of the DTPA chelator at the N-terminus of the B-chain and subsequent loading of a lanthanide (europium) ion into the chelator led to a labeled peptide (Eu-DTPA-(B)-H2) in low yield and having very poor water solubility. On the other hand, coupling of the DTPA and loading of Eu at the N-terminus of the A-chain led to a water-soluble peptide (Eu-DTPA-(A)-H2) with a significantly improved final yield. The conjugation of the DTPA chelator at the N-terminus of the A-chain did not have any impact on the secondary structure of the peptide determined by circular dichroism spectroscopy (CD). On the other hand, it was not possible to determine the secondary structure of Eu-DTPA-(B)-H2 because of its insolubility in phosphate buffer. The B-chain labeled peptide Eu-DTPA-(B)-H2 required solubilization in DMSO prior to carrying out binding assays, and showed lower affinity for binding to H2 relaxin receptor, RXFP1, compared to the water-soluble A-chain labeled peptide Eu-DTPA-(A)-H2. The mono-Eu-DTPA labeled A-chain peptide, Eu-DTPA-(A)-H2, thus can be used as a valuable probe to study ligand-receptor interactions of therapeutically important H2 relaxin analogs. Our results show that it is critical to choose an approriate site for incorporating chelators such as DTPA. Otherwise, the bulky size of the chelator, depending on the site of incorporation, can affect yield, solubility, structure and pharmacological profile of the peptide. 相似文献