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Smaller Molecules (smaller + molecule)
Selected AbstractsCatalytic digestion of human tumor necrosis factor-, by antibody heavy chainFEBS JOURNAL, Issue 18 2010Emi Hifumi It has long been an important task to prepare a catalytic antibody capable of digesting a targeting crucial protein that controls specific life functions. Tumor necrosis factor-, (TNF-,) is a cytokine and an important molecule concerned with autoimmune diseases such as rheumatoid arthritis, chronic obstructive pulmonary disease, and Crohn's disease. A mAb (ETNF-6 mAb) raised against human TNF-, was prepared, and the steric conformation was created by using molecular modeling after the cDNA was sequenced. The heavy chain (ETNF-6-H) of the mAb was considered to possess a catalytic triad-like structure in the complementarity determining regions (CDRs). As a result, ETNF-6-H exhibited a peptidase and a protease activity. In fact, ETNF-6-H predominantly cleaved the Ser5-Arg6 bond of TNF-, at the first step, resulting in the generation of a fragment of , 17 kDa. This fragment was digested to a smaller molecule of 15 kDa by scission of the Gln21-Ala22 bond. The intermediate product was further converted into a fragment of 13.3 kDa by successive cleavage of the Leu36-Leu37 and Asn39-Gly40 bonds. The heavy chain possessed a protease activity against TNF-, with a multicleavage site. [source] Diffusion Characteristics of VOCs IndoorsIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2010Shin-ichi Shibata Student Member Abstract Diffusion characteristics of volatile organic compounds (VOCs) were investigated indoors using tin oxide gas sensors. The chemicals cause various kinds of symptoms in humans, for example, the sick house syndrome. In this study, eight sensors were installed in a vertical direction and on a plane surface. These sensors were of the same type. The VOC is placed in a generation source, and the sensor output increases as the chemical diffuses. The sensor output becomes higher as the concentration increases. The following chemicals were tried as air pollutants: formaldehyde, toluene, and xylene. The sensor output changes in short, quick steps by slight fluctuations of the wind velocity. Therefore, the differential characteristic of the sensor output was adopted and the noise component was removed as far as possible. A threshold time tth to the characteristic was set up. It is assumed that the examining chemical reaches the installed sensor point in a time greater than this time. The new speed of arrival is proposed using the threshold time. The speed s [cm/min] is indicated using the distance d and the reaching time tth, namely, s = d/tth. Here, d means the distance between the sensor position and the polluting source. As a result, the speed for the sensor that is installed near the ceiling (at a height of 260 cm from the floor) is the highest. And, it became obvious that s was larger for the chemical with a smaller molecule. The speed of formaldehyde for the sensor installed near the ceiling was 700 cm/min and that for the sensor installed at the height of 100 cm from the floor was 370 cm/min. There is almost a two times difference in the speed. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Production of Resistant Starch by Extrusion Cooking of Acid-Modified Normal-Maize StarchJOURNAL OF FOOD SCIENCE, Issue 7 2009Jovin Hasjim ABSTRACT:, The objective of this study was to utilize extrusion cooking and hydrothermal treatment to produce resistant starch (RS) as an economical alternative to a batch-cooking process. A hydrothermal treatment (110 °C, 3 d) of batch-cooked and extruded starch samples facilitated propagation of heat-stable starch crystallites and increased the RS contents from 2.1% to 7.7% up to 17.4% determined using AOAC Method 991.43 for total dietary fiber. When starch samples were batch cooked and hydrothermally treated at a moisture content below 70%, acid-modified normal-maize starch (AMMS) produced a greater RS content than did native normal-maize starch (NMS). This was attributed to the partially hydrolyzed, smaller molecules in the AMMS, which had greater mobility and freedom than the larger molecules in the NMS. The RS contents of the batch-cooked and extruded AMMS products after the hydrothermal treatment were similar. A freezing treatment of the AMMS samples at ,20 °C prior to the hydrothermal treatment did not increase the RS content. The DSC thermograms and the X-ray diffractograms showed that retrograded amylose and crystalline starch,lipid complex, which had melting temperatures above 100 °C, accounted for the RS contents. [source] Kinetic Study of Thermally Induced Inulin GelJOURNAL OF FOOD SCIENCE, Issue 7 2001Y. Kim ABSTRACT: Heated inulin solution undergoes a sol-gel transition during cooling and forms a white smooth gel under optimized conditions. The degree of gel formation is negatively related to hydrolysis of inulin during heating. Heating makes inulin soluble; overheating causes hydrolysis of dissolved inulin into smaller molecules. Using a 2-step model including a solubilization step and a hydrolysis of inulin step, we found that both steps follow pseudo first-order kinetics. Separate studies on initial rates of the solubilization and hydrolysis of inulin steps at constant temperatures show that the solubilization rate of inulin is much faster than that of the hydrolysis of inulin. Gel formation of inulin may be related to the average chain length of inulin after heating. [source] Bioaffinity chromatography on monolithic supportsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 3 2010Kishore K. R. Tetala Abstract Affinity chromatography on monolithic supports is a powerful analytical chemical platform because it allows for fast analyses, small sample volumes, strong enrichment of trace biomarkers and applications in microchips. In this review, the recent research using monolithic materials in the field of bioaffinity chromatography (including immunochromatography) is summarized and discussed. After giving an introduction into affinity chromatography, information on different biomolecules (antibodies, enzymes, lectins, aptamers) that can act as ligands in bioaffinity chromatography is presented. Subsequently, the history of monoliths, their advantages, preparation and formats (disks, capillaries and microchips) as well as ligand immobilization techniques are mentioned. Finally, analytical and preparative applications of bioaffinity chromatography on monoliths are presented. During the last four years 37 papers appeared. Protein A and G are still most often used as ligands for the enrichment of immunoglobulins. Antibodies and lectins remain popular for the analysis of mainly smaller molecules and saccharides, respectively. The highly porous cryogels modified with ligands are applied for the sorting of different cells or bacteria. New is the application of aptamers and phages as ligands on monoliths. Convective interaction media (epoxy CIM disks) are currently the most used format in monolithic bioaffinity chromatography. [source] Accelerator mass spectrometry offers new opportunities for microdosing of peptide and protein pharmaceuticalsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 10 2010Mehran Salehpour Accelerator Mass Spectrometry (AMS) is an ultra-sensitive analytical method which has been instrumental in developing microdosing as a strategic tool in early drug development. Considerable data is available for AMS microdosing using typical pharmaceutical drugs with a molecular weight of a few hundred Daltons. The so-called biopharmaceuticals such as proteins offer interesting possibilities as drug candidates; however, experimental data for protein microdosing and AMS is scarce. The analysis of proteins in conjunction with early drug development and microdosing is overviewed and three case studies are presented on the topic. In the first case study AMS experimental data is presented, for the measured concentration of orally administered recombinant insulin in the blood stream of laboratory rabbits. Case study 2 concerns minimum sample size requirements. AMS samples normally require about 1,mg of carbon (10,µL of blood) which makes AMS analysis unsuitable in some applications due to the limited availability of samples such as human biopsies or DNA from specific cells. Experimental results are presented where the sample size requirements have been reduced by about two orders of magnitude. The third case study concerns low concentration studies. It is generally accepted that protein pharmaceuticals may be potentially more hazardous than smaller molecules because of immunological reactions. Therefore, future first-in-man microdosing studies might require even lower exposure concentrations than is feasible today, in order to increase the safety margin. This issue is discussed based on the current available analytical capabilities. Copyright © 2010 John Wiley & Sons, Ltd. [source] Molecular mass ranges of coal tar pitch fractions by mass spectrometry and size-exclusion chromatographyRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2009F. Karaca A coal tar pitch was fractionated by solvent solubility into heptane-solubles, heptane-insoluble/toluene-solubles (asphaltenes), and toluene-insolubles (preasphaltenes). The aim of the work was to compare the mass ranges of the different fractions by several different techniques. Thermogravimetric analysis, size-exclusion chromatography (SEC) and UV-fluorescence spectroscopy showed distinct differences between the three fractions in terms of volatility, molecular size ranges and the aromatic chromophore sizes present. The mass spectrometric methods used were gas chromatography/mass spectrometry (GC/MS), pyrolysis/GC/MS, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) and laser desorption time-of-flight mass spectrometry (LD-TOFMS). The first three techniques gave good mass spectra only for the heptane-soluble fraction. Only LDMS gave signals from the toluene-insolubles, indicating that the molecules were too involatile for GC and too complex to pyrolyze into small molecules during pyrolysis/GC/MS. ESI-FTICRMS gave no signal for toluene-insolubles probably because the fraction was insoluble in the methanol or acetonitrile, water and formic acid mixture used as solvent to the ESI source. LDMS was able to generate ions from each of the fractions. Fractionation of complex samples is necessary to separate smaller molecules to allow the use of higher laser fluences for the larger molecules and suppress the formation of ionized molecular clusters. The upper mass limit of the pitch was determined as between 5000 and 10,000,u. The pitch asphaltenes showed a peak of maximum intensity in the LDMS spectra at around m/z 400, in broad agreement with the estimate from SEC. The mass ranges of the toluene-insoluble fraction found by LDMS and SEC (400,10,000,u with maximum intensity around 2000,u by LDMS and 100,9320,u with maximum intensity around 740,u by SEC) are higher than those for the asphaltene fraction (200,4000,u with maximum intensity around 400,u by LDMS and 100,2680,u with maximum intensity around 286,u by SEC) and greater than values considered appropriate for petroleum asphaltenes (300,1200,u with maximum intensity near 700,u). Copyright © 2009 John Wiley & Sons, Ltd. [source] Transformation of organic molecules on the low-valent {M(Ph2PCH2CH2PPh2)2} moiety derived from trans -[M(N2)2(Ph2PCH2CH2PPh2)2] or related complexes (M = MO, W)THE CHEMICAL RECORD, Issue 5 2001Hidetake Seino Abstract A zero-valent {M(Ph2PCH2CH2PPh2)2} moiety (M = Mo, W) generated in situ by dissociation of the N2 ligands in trans -[M(N2)2(Ph2PCH2CH2PPh2)2] can activate ,-accepting organic molecules including isocyanides and nitriles, which undergo the electrophilic attack caused by a strong ,-donation from a zero-valent metal center. Cleavage of a variety of C,X bonds (X = H, C, N, O, P, halogen) also occurs at their electron-rich sites through oxidative addition to form reactive intermediates, which subsequently degradate to yield smaller molecules either bound to or dissociated from the metal center. The mechanism is substantiated unambiguously by isolation of numerous intermediate stages. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:349,361, 2001 [source] | ||||||||||