摘要:

AbstractIn comparison with the relatively complicated flagella of all nucleated organisms, most of the actively motile bacteria have very much simpler locomotion organelles. These flagella are long thin filaments with a helical superstructure, anchored at one end in the cell membrane. Helical waves pass along the flagella in the distal direction during locomotion. In the flagella, identical structural units of a single protein species, flagellin, are linked to one another by non‐covalent bonds. The flagellin subunits can be separated from one another by mild methods, and their biochemistry as well as their structure and morphology can be investigated in the isolated state. Under certain conditions they can reaggregate in vitro to form polymorphous helical filaments, which are practically indistinguishable from intact flagella. In the flagellum, the elongated flagellin molecules have a layered arrangement in about ten parallel strands, which in turn form a hollow cylinder. Since this cylinder is deformed into a large helix, the individual chemically identical flagellin protomers and the protomer strands in the helical flagella are only quasi‐equivalent. The conformation and bonding pattern of the individual longitudinal flagellin lines can presumably be controlled in vitro by the basal structures, so that movement within the flagellum could conceivably occur as follows. A cyclically induced change in the length of the individual strands could result in an apparent rotation of the helical flagellum. According to hydrodynamic calculations, the resulting forward thrust is sufficient to propel the bacteria at the observed speeds of up to 50

ISSN:0570-0833    

DOI:10.1002/anie.197306831

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractExperimental studies on compounds of alkali and alkaline earth metals with semi‐ and metametals have considerably broadened the basis for a discussion of the transition from metallic to ionic bonding. Current interest is focused mainly upon the elucidation of the principles governing the structure of such compounds which are subject to a wide range of variation within this class of materials. A new definition of the term Zintl phase is proposed after consideration of available finding

ISSN:0570-0833    

DOI:10.1002/anie.197306941

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractNuclear‐medical diagnostic methods are widely used at present, examples being localization diagnosis e.g. of the thyroid, the kidney, and the spleen and function tests,e.g.on the thyroid and on the liver. For these tests it is essential to have organ‐specific vehicle substances that can be labeled with suitable radionuclides. Forin‐vivoinvestigations, the exposure of the patient to radiation should be kept as small as possible, but the radiation must nevertheless be sufficient to allow the detection of the nuclide. Today, the therapeutic use of radionuclides is only small in comparison with their use in diag

ISSN:0570-0833    

DOI:10.1002/anie.197307121

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe glycoproteins exercise important biological functions as transport proteins, inhibitors, enzymes, hormones, complement factors, and immunoglobulins. Their chemistry is characterized by a number of rules. Thus only asparagine, threonine, or serine can carry the oligosaccharide groups; for the N‐acylglycosylamine linkage involving asparagine, the grouping Asn‐X‐Thr or Asn‐X‐Ser is always present in the peptide chain. However, practically no agreement is found in the molecular weights of the glycoproteins, their carbohydrate contents, and the relative contents of the‐various sugars. The biological significance of the carbohydrate fraction has not yet been explained, but some idea of the part played by the easily removable neuraminic acid is b

ISSN:0570-0833    

DOI:10.1002/anie.197307211

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe results of (low energy) photoelectron spectroscopy render possible a better appreciation of the “Nature of the Chemical Bond”. The application of this new experimental method is demonstrated utilizing representative compounds of the nonmetal elements, and a close symbiosis delineated with molecular orbital models. In particular, general consequences are discussed concerning electron deficiency, σ‐ and π‐interactions, electron pair delocalization, and substituent effects or geometric perturbations. Photoelectron spectroscopic ionization energies permit evaluation of parameters for specified molecular groups, allow correlation with numerous other experimental data, and are didactically valuable in the teaching of general

ISSN:0570-0833    

DOI:10.1002/anie.197307341

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197307521

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197307531

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197307541

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197307561

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197307571

出版商:Hüthig&Wepf Verlag    

年代:1973

数据来源: WILEY