TheBiophysicalSociety of Japan General IncorporatedAssociation equal to the X phage repressor ",as randomly generated. The point mutagenesis was introduced at each generatjon, and with thus generated sequence, conformationwascalcutatedwirhacombinedmethodofthefragmentassembly and Langevin dynamics calculatiolls. The mutated sequence was selec;cd according to tbe cT{terion whether the calcutated eonformutien has a loca] structure of the active residues more similar to that ofthe). ph age repressor. We discuss the numerical resu]ts of this simulated cvolution. Science and Tkehnology, Antibodies exist in bloed or body fiuid, and they recognize and bind a variety of bacterium and viruses which invade the body and the ccll as antigens. Antibodies genera]]y form Y-shaped tctramer composed oftwo lj.trht chains and two heavy chains. That is, thc dimerization ofthe VH domain and the VL demain, beth of which are variable regions ofantibodies are Tequired for function as an antibody. On thc other hand, many carnclid antibodies composed orenly two heavy chains have been known that only VH domain play a role as antibodies. This single domain antigen, so called nanobody. is much simpler than a com,cntional antibody ill point of chernical eemposjtion and form. And it is expected as a various applications for its specifieity in the field of medicjne and biophysics. Espeeially according to the repert, cVH-E2 antibody which has high-uennity and variant efhypervariable regions tbr antigen binding site is aii effective inhibitor ofNS3 serine pTotease which is kcy enzyme of the hepatitis C virus, In this study, "'e carried out the motecular dynamics simuTations of cVH-E2 monomer obtained from X-ray crysta]lography and solution NMR structurc VIi-P8. The VH-P8 is a precursor to cVH-E2, and different in the amino acid sequences of hypervariable regions and VL-binding face. From these calculations, we will discuss the conformationa] fiuctuations of hypen,ariable regions and difference of conformationat stability of VL-binding face gn solution, CguffWV(JbXI[6{i6NS3UU;,7Df7-U'coPE:rn cvH #1[ eeYUhNh\V:-=V-YiY Gt'aduate School of Natural Kanazawa Unii,ersi",) 3Gtri24 Hiremi 7:-1getNe7thpteMLIte B-sheet rvntiMllMcoeeff (2) Development ot' prediction method for fi-sheet formation using amino acid pairing propensity (2) Suzuki (Sehool ofAgri., Meiii Univ) We have been developing a prediction method for P-sheet forination using stat{stical scores computed from the frequency ofthe inter-strand amino acid residue pairs based on experimental protejn structure data, taking the cxistence ofhydrogen bond formation into aeeount These scores showed that residues on a strand tend to avoid inconvenient residucs on the other strand as partners (negativc selection) rather than to select convenient rcsidues (positive se!ection). Prcdiction accuracies tbr strand order in the P-sheets using these scores were S8, 3S, 20 and 14% for3-, 4-, 5-and 6-stranded sheets, respectis,ely, and up to 77, 57. 39 and 22% by adding two rcstrictions/ i) Strands fonn anti-paral...

Monitoring of food products from animal origin for the presence of antimicrobial residues is preferably done using microbial screening methods because of their high cost-effectiveness. Traditionally applied methods fail to detect the maximum residue limits which were established when EU Council Regulation 2377/90 came into effect. Consequently, during the last decade this has led to the development of improved microbial screening methods. This review provides an overview of the efforts expended to bring antibiotic screening methods into compliance with EU legislation. It can be concluded that the current situation is still far from satisfactory.FigureMicrobial inhibition assay for muscle samples

Comparing the sensitivity of algal, cyanobacterial and bacterial bioassays to different groups of antibiotics van der Grinten, E.; Pikkemaat, M.G.; van den Brandhof, E.J.; Stroomberg, G.J.; Kraak, M.H.S. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. a b s t r a c tAntibiotics may affect both primary producers and decomposers, potentially disrupting ecosystem processes. Hence, it is essential to assess the impact of antibiotics on aquatic ecosystems. The aim of the present study was therefore to evaluate the potential of a recently developed test for detecting antibiotics in animal tissue, the Nouws Antibiotic Test (NAT), as a sensitive bioassay to assess the effects of antibiotics in water. To this purpose, we determined the toxicity of sulphamethoxazole, trimethoprim, flumequine, tylosin, streptomycin, and oxytetracycline, using the NAT adapted for water exposure. The sensitivity of the NAT was compared to that of bioassays with bacteria (Microtox), cyanobacteria and green algae. In the Microtox test with Vibrio fischeri as test organism, no effects were observed for any of the test compounds. For three of the six antibiotics tested, the cyanobacteria were more vulnerable than the green algae when using photosynthetic efficiency as an endpoint. The lowest EC50 values for four out of six tested antibiotics were obtained using the NAT bacterial bioassay. The bacterial plate system responded to antibiotics at concentrations in the lg L À1 and lower mg L À1 range and, moreover, each plate proved to be specifically sensitive to the antibiotics group it was designed for. It is concluded that the NAT bioassay adapted for water exposure is a sensitive test to determine the presence of antibiotics in water. The ability of this test to distinguish five major antibiotic groups is a very strong additional value.

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Tetracycline (TC) specific luminescent bacterial biosensors were used in a rapid TC residue assay sensitized to meet the EU maximum residue limit (MRL) for TC residues in poultry muscle tissue (100 microg kg(-1)) by membrane-permeabilizing and chelating agents polymyxin B and EDTA. Sensitivities of 5 ng g(-1) for doxycycline, 7.5 ng g(-1) for chlortetracycline, and 25 ng g(-1) for tetracycline and oxytetracycline were reached. Except for doxycycline, the MRLs of these tetracyclines include their 4-epimer metabolites. In the biosensor assay, all four 4-epimers showed induction capacity and antimicrobial activity, and antimicrobial activity was also observed in the inhibition assay, although with lower efficiency than that of the corresponding parent compound in both assays. The biosensor assay is an inexpensive and rapid high-throughput screening method for the detection of 4-epimer TC residues along with their parent compounds.