The Accumulation of Heavy Metals and 137Cs in Plant Products Grown on Radioactively Contaminated Chernozems of Tula Oblast

The results of studies of three sites of agrocenoses are presented: wheat (seed cereals), soybeans (legumes) and legume-cereal (rumpgoatskin) perennial grass mixtures to identify the peculiarities of the transition of stable and radioactive pollutants (including substances of hazard classes 1 and 2 and 137Cs) in the system "agro-chernozems – agricultural plants" with soil testing and quality control of aerial and underground plant phytomass. In this radioactively contaminated area, the elemental composition of wheat, soybean, rump and goatskin does not differ from the composition of the corresponding species in the background. Legumes have an increased need for alkaline earth metals (Ca, Mg, Sr) and also contain more Ni and Mn, cereals – in Si. Within the studied part of Plavsky radioactive spot, the quality of agricultural products meets the relevant standards for the content of heavy metals and 137Cs.

Notizen: Lysine as the Substrate Binding Site of Porphobilinogen Synthase of Rhodopseudomonas spheroides

The 14C labelled inactive protein obtained by sodium borohydride reduction of the enzyme, porphobilinogen synthase of Rhodopseudomonas spheroides, in the presence of [4-14C] 5-aminolevulinic acid, gave on acid hydrolysis and subsequent electrophoresis or two-dimensional chromatography a major radioactive spot which was confirmed to be N -ε-[4-(-5aminovaleric acid)] lysine (ALA-lysine) by comparing its co-chromatographic and electrophoretic be ­ haviour with the chemically synthesized ALA-lysine. An ε-NH, group of lysine residue of porphobilinogen synthase, is thus the binding site of the substrate, 5-aminolevulinic acid.

Strahleninduzierte Aggregatbildung von Proteinen: Bindung von Aminosäuren an Myoglobin / Radiation-Induced Aggregation of Proteins: Binding of Amino Acids to Myoglobin

When myoglobin is irradiated in the presence of amino acids, the most radiation-reactive species, like the aromatic and sulfur-containing amino acids, will bind preferentially to the protein. The radiation-induced binding is strongly dependent on the concentration of protein and amino acid. Subsequent to irradiation of myoglobin in the presence of radioactively labelled tryptophan followed by tryptic hydrolysis, only a single radioactive spot was detected on the fingerprint. The binding of amino acids is thus not randomly distributed over the protein molecule but occurs at specific reactive sites.

Biotin transport by small intestine of rat, hamster, and other species

At a concentration of 1 x 10–5 m, biotin-H3 and biotin-C14 were transported against a concentration gradient by hamster everted intestinal sacs. Similar transport was shown by the small intestine of the white mouse, Mongolian gerbil, chinchilla, flying squirrel, round-tail squirrel, Malayan black squirrel, and chipmunk (and was maximal in the chipmunk intestine). Transport under these conditions was not shown by the small intestine of the rat, rabbit, guinea pig, ferret, or carp. There does not appear to be a correlation between the need for biotin as a vitamin in a species and the presence of this transport system. Chromatography of the mucosal and serosal solutions did not reveal any radioactive spot other than the original biotin-H3 or biotin-C14. This evidence, plus the inhibition of transport by avidin, suggests that it is biotin that is being transported, and not a metabolite. The unidirectional flux of biotin (from a side containing the vitamin to a side which did not), was uninfluenced by the addition of avidin to the buffer into which diffusion was occurring. The "apparent Km" for biotin transport was on the order of 6 x 10–5 m, based on equilibrium measurements. Transport of biotin in the hamster small intestine occurred principally in the first one-third to one-half of the small intestine. Amino acids, urea, biotin- d-sulfoxide, as well as biotin- l-sulfoxide did not inhibit biotin transport. Biocytin, biotin methyl ester, diaminobiotin, desthiobiotin, thioctic acid, and two other analogues inhibited biotin transport.