Febs Letters

doi: 10.1016/0014-5793(83)81148-Xpmid: N/A

Briat, Jean François; Dron, Michel; Mache, Régis

doi: 10.1016/0014-5793(83)81149-1pmid: N/A

Three stem‐loop structures (H1, H2, H3) can be formed in the leader transcript of the chloroplast rDNA of spinach, tobacco and maize. H2 and H3 partially overlap and cannot exist simultaneously. These potential hairpins lead us to postulate that higher plant chloroplast rDNA is regulated by premature termination. This mechanism could be controlled by the presence or absence of a ribosome translating an hypothetical leader peptide encoded in the rDNA leader sequence of these 3 higher plants.

Goodall, G.J.; Prager, R.; Wallace, J.C.; Keech, D.B.

doi: 10.1016/0014-5793(83)81150-8pmid: 6628689

Previous proposals for the mechanism by which biotin‐dependent enzymes catalyse the transfer of the carboxyl group from 1'‐N‐carboxybiotin to acceptor molecules do not appear to be consistent with all of the experimental observations now available. We propose a multi‐step mechanism in which (a) substrate and then carboxybiotin bind at the second partial reaction site, (b) a base positioned adjacent to the 3'‐N of the carboxybiotin abstracts a proton from the 3'‐N and (c) the resulting enolate ion and the acceptor substrate undergo a concerted reaction resulting in carboxyl‐group transfer.

Parkkinen, J.

doi: 10.1016/0014-5793(83)81151-Xpmid: 6628680

Three inositol‐containing sialyloligosaccharides were isolated from normal human urine. Structural studies including gas—liquid chromatography of mono‐ and disaccharide derivatives, methylation analysis, mass spectrometry and glycosidase treatments indicated the structure NeuAc (α2–3)Gal(β1‐0)scyllo‐inositol for one of the oligosaccharides isolated. This provides the first evidence for the natural occurrence of a scyllo‐inositol glycoside in biological material. The two other oligosaccharides isolated were identified as two isomers of NeuAc(α2–3)Gal(β1‐0)myo‐inositol, which have not been identified in normal urine before.

Rudloff, V.; Lepke, S.; Passow, H.

doi: 10.1016/0014-5793(83)81152-1pmid: 6628684

The inhibition of anion transport by dinitrophenylation of the red cell membrane is brought about by the modification of a single lysine residue located on the 17‐kDa segment of the band 3 protein. This residue is identical with Lys a, which is also capable of reacting with one of the two isothiocyanate groups of 4,4'‐diisothiocyano dihydro‐stilbene‐2,2'‐disulfonate (H2DIDS). The rate of reaction between Lys a and 1‐fluoro‐2,4‐dinitrobenzene is reduced when a second lysine residue on the 35‐kDa segment of the band 3 protein becomes dinitrophenylated. This latter residue is not identical with Lys b which is known to be present on the 35‐kDa segment and involved in the cross‐linking of this segment with the 17‐kDa segment by H2DIDS.

Geisler, Norbert; Plessmann, Uwe; Weber, Klaus

doi: 10.1016/0014-5793(83)81153-3pmid: 6628686

The amino‐terminal 98 residues of porcine vimentin have been determined by amino acid sequence studies. Extensive overlap is seen with the corresponding region of the carboxyterminal 448 residues of hamster vimentin predicted from DNA sequence studies, which left the very amino‐terminal region unknown. The combined data show that contrary to gel electrophoretic results, mammalian vimentin contains only about 467 residues, and that species‐specific drift occurs mainly in the amino‐terminal non‐α‐helical array. The results are discussed parallel to emerging concepts on intermediate filament protein diversity.

Prince, Roger C.; Larroque, Christian; Hooper, Alan B.

doi: 10.1016/0014-5793(83)81154-5pmid: 6628687

Optical spectroscopy combined with redox potentiometry has resolved the hemes of hydroxylamine oxidoreductase into 6 thermodynamically distinct classes. There are apparently 4 classes of heme c 553, with E m7‐values of 295 mV, 10 mV, −190 mV and −390 mV, present in a stoichiometry of 1:1:2:1; two equivalents of heme c 559, E m7 O mV, and one of heme P‐460, an unusual chromophore, with E m7 −260 mV.

Wingender-Drissen, Ruth

doi: 10.1016/0014-5793(83)81155-7pmid: 6354751

We have purified cyclic AMP‐dependent protein kinase from the yeast Saccharomyces cerevisiae. The purified enzyme was inactive in the absence of cyclic AMP and displayed two protein bands on SDS gel electrophoresis. One was identified as the cAMP‐binding protein by chromatography on cAMP‐agarose. M r of the latter was 50 000 while the catalytic subunit had an M r of 59 000. The enzyme accepted yeast phosphorylase, glycogen synthase and fructose 1,6‐bisphosphatase as substrates. No inhibition by the mammalian protein kinase inhibitor was observed.

Wingender-Drissen, Ruth; Becker, Jörn Ullrich

doi: 10.1016/0014-5793(83)81156-9pmid: 6354752

Yeast phosphorylase is phosphorylated and activated by a cyclic AMP‐independent protein kinase (called phosphorylase kinase) and a cyclic AMP‐dependent protein kinase. Only in the presence of both kinases is phosphorylase fully activated and phosphorylated. No evidence was found for the presence of two phosphorylation sites as an identical phosphopeptide pattern of phosphorylase is obtained after phosphorylation by either one or both kinases. The kinases probably phosphorylate identical sites but recognize different subunits of phosphorylase. Phosphorylase kinase phosphorylates the high‐M r subunit while cAMP‐dependent protein kinase phosphorylates the low‐M r subunit.

Bányai, László; Váradi, András; Patthy, László

doi: 10.1016/0014-5793(83)81157-0pmid: 6685059

Comparison of the primary structures of high‐M r urokinase and tissue‐type plasminogen activator reveals a high degree of structural homology between the two proteins, except that tissue activator contains a 43 residue long amino‐terminal region, which has no counterpart in urokinase. We show that this segment is homologous with the finger‐domains responsible for the fibrin‐affinity of fibronectin. Limited proteolysis of the amino‐terminal region of plasminogen activator was found to lead to a loss of the fibrin‐affinity of the enzyme. It is suggested that the finger‐domains of fibronectin and tissue‐types plasminogen activator have similar functions and that the finger‐domains of the two proteins evolved from a common ancestral fibrin‐binding domain.