. which have been named transcobalamin 1 and 2 by Hall and Finkler.4 \Vhen serum which contains radioactive vitamin B12 is filtered through sephadex, the radioactivity appears in the effluent in fractions corresponding to molecular weights of 121,000 and 36,000. It has been assumed that these fractions correspond to association of the B12 with TC1 and TC2, respectively. It has been reported tha...

The discovery of microbial metabolites—macrotetrolides, siderochromes and boromycin—is reviewed. The structures of these and related compounds provide instructuve examples of how Nature has solved the problem of cornplexing certain rarer elements, such as potassium, iron and boron. The common structural features of these highly specific, natural complexing agents are briefly discussed. It was e...

Understanding of structure–affinity relationships is crucial for rational receptor design, however, such studies for anion receptors are still limited. Therefore, we investigated this issue in the case of amide-based macrocyclic receptors derived from aromatic diacids (i.e., isophthalic and dipicolinic). Using these model compounds, we examined the macrocyclic effect, the influence of intramole...

By means of potentiometric titrations, the copper-complcxing properties of organic compounds released by 21 algal species are characterized. Most eucaryotic species relcascd measurablc amounts (lo-” M) of copper-complexing agents that could be modeled as weak organic acids with log{*&.,,,} = 0.5. Of seven blue-green algal species studied, four produced about 5 x lo+ M concentrations of strong c...

für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution 4.0 International License. Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Creative Commons Namen...

Most studies of the organic complexation of Cu in natural waters have focused on distributions and processes in the water column, where a significant fraction of Cu-complexing ligands may be biologically produced. We present direct evidence for a flux of Cu-complexing ligands from estuarine sediments, demonstrating that sediments are a significant, yet previously unrecognized source of the liga...

We have studied the kinetics of copper uptake by apoazurin in imidazole and 1-methylimidazole buffers in the pH range of 7-9 with mu = 0.5 M and copper(II) in large excess. The reaction has been monitored by measuring the visible absorbance and circular dichroism as a function of time. The uptake occurs in a stepwise fashion, and at least two intermediates are implicated. Overall, the rate of u...

A monofunctionalised pillar[5]arene derivative carrying a viologen side chain which exhibits self-complexation in dilute dichloromethane solutions forms supramolecular daisy chain polymers and eventually organogels as its concentration is increased three-fold over the range from 0.1 to 100 mM.

Synthesis of new podands from resorcinarene and diethylene glycols are reported. The binding properties of these podands with alkali metal cations was studied by means of ESI-MS. The experimental results for podands with long diethylene glycol arms show the stable inclusion complexes with one or two metal cations and high affinity for sodium and potassium ions. This podands under appropriate co...

A case of transcobalamin II deficiency with several unique features is described. The clinical presentation was typical. except for a slightly delayed age at presentation and the occurrence of apparent neurologic dysfunction from the beginning. The unusual biochemical feature was a low serum cobalamin level (97 pg/mI). Several cobalaminbinding protein abnormalities coexisted and antedated cobal...