Developmental biochemistry of cottonseed embryogenesis and germination. XIX. Sequences and genomic organization of the α globulin (vicilin) genes of cottonseed

The q7123424/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> globulin storage protein genes of cotton are found to exist as gene tandems that contain a gene from each of the 2 q7123424/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> globulin subfamilies separated by a spacer region of about 2700 or 3400 base pairs. Three different tandems have been identified by restriction endonuclease mapping of genomic DNA. A cDNA that is different from the genes of the tandems in map sites and/or in nucleotide sequence indicates that a fourth tandem probably exists in the cotton genome. Since the species of cotton used here (Gossypium hirsutum) is an amphidiploid, it is likely that two of the tandems are contributed from each genome.Considerable divergence in nucleotide sequence (18%) and in derived amino acid sequence (28%) is found when the 2 genes of a sequenced tandem are compared. The sequence of the cDNA closely resembles one of the genes in the tandem showing only a 4% divergence in nucleotides and a 4.2% divergence in amino acids. Thus the 2 genes of each tandem represent a relatively ancient gene duplication that has given rise to the two q7123424/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> globulin subfamilies of cotton. Only one subfamily has a glycosylation site and the glycosylation of its derived proteins gives rise to the 2 molecular weight sets of q7123424/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> globulins seen on gel electrophoresis.Other basic features of these genes and their derived proteins are presented.     

Photoinactivation of δ-aminolevulinic acid dehydratase from maize by flavin mononuclotide

The q786l/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">-aminolevulinic acid dehydratase activity was irreversibly inactivated by irradiation of the enzyme in presence of flavin mononucleotide. The loss of enzyme activity was dependent on time of irradiation, concentration of FMN and intensity of irradiance. It required oxygen and was markedly enhanced in heavy water. The presence of levulinic acid (a competitive inhibitor of q786l/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">-ALAD) during irradiation prevented the inactivation considerably indicating photooxidative damage at or near the active site. Superoxide dismutase, sodium benzoate and sodium formate offered no protection, but singlet oxygen quenchers like azide and tryptophan were effective. NADH, electron donor to excited flavins, also prevented the loss of enzyme activity. These results indicate that singlet oxygen produced by light absorption of FMN was responsible for the photooxidative inhibition of the enzyme.Abbreviations q786l/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">ALAD q786l/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">-aminolevulinic acid dehydratase - FMN flavin mononucleotide - O₂ ^- superoxide - H₂O₂ hydrogen peroxide - 10₂ singlet oxygen - LA levulinic acid - PBG porphobilinogen - BSA bovine serum albumin - BME 2-mercaptoethanol - SOD superoxide dismutase - pHMB para-hydroxymercuribenzoate - DTT dithiothreitol - FAD flavin adenine dinucleotide - NADH nicotinamide adenine dinucleotide     

Adenine nucleotide contents and energy charge of Azotobacter vinelandii grown at low phosphate concentration

The effect of a low phosphate concentration on intracellular adenine nucleotide content, oxygen consumption and poly-q7/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-hydroxybutyrate deposition was investigated with N-free and NH ₄ ⁺ batch cultures of Azotobacter vinelandii. When the microorganisms were cultured under low-phosphate concentrations the cells contained much larger amounts of poly-q7/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-hydroxybutyrate, but displayed lower oxygen consumption activities and energy charge values than did control cells. Also, the ratio ATP to ADP was much higher in control cells and the intracellular levels of ATP were lower in low-phosphate cells.     

High-affinity uptake of γ-[3H]aminobutyric acid by isolated mouse oligodendrocytes in culture

Oligodendrocytes were isolated from mixed glial cultures of neonatal mouse forebrain and further grown in serum-free hormone supplemented culture medium. Cell populations were identified by indirect immunofluorescence using a range of specific antibodies, revealing a predominantly immature population of oligodendrocytes, the majority expressing the myelin glycolipids galactocerebroside and sulfatide on their plasma membrane. Astroglial contamination was found to be minimal. Simultaneous autoradiography and immunofluorescence demonstrated the presence of a transport system for the major inhibitory neurotransmitter GABA in the oligodendrocytes. The transport system was found to be energy, sodium and temperature dependent. Kinetic analysis revealed a high affinity system, with aK _m of 6.27 q67/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M and aV _max of 0.714 nmol/min/mg protein, which is comparable to that found previously for CNS neurons and astrocytes.Special Issue dedicated to Dr. E. M. Shooter and Dr. S. Varon.     

Enzymic synthesis,chemical characterisation and Sda activity of GalNAcß1-4[NeuAcα2-3]Galß1-4GlcNAc and GalNAcß1-4[NeuAcα2-3]Galß1-4Glc

The tetrasaccharides GalNAcß1-4[NeuAcq276245v4/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">2-3]Galß1-4Glc and GalNAcß1-4[NeuAcq276245v4/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3q276245v4/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-sialyllactose (NeuAcq276245v4/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">2-3Galß1-4Glc) and 3q276245v4/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-sialyl-N-acetyllactosamine (NeuAcq276245v4/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">2-3Galß1-4GlcNAc). The structures of the products were established by methylation and¹H-500 MHz NMR spectroscopy. In Sd^a serological tests the product formed with 3q276245v4/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-sialyl-N-acetyllactosamine was highly active whereas that formed with 3q276245v4/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-sialyllactose had only weak activity.     

C1q,a collagen-like complement subcomponent,in dermatosparactic cattle: its extracellular modification is not affected by lack of procollagen N-terminal proteinase (pN-proteinase)

C1q, a collagen-like complement protein, was purified from the serum of a ddermatosparactic calf which lacks procollagen N-terminal proteinase (pN-proteinase). The specific hemolytic activity of the serum Clq from the dermatosparactic animal was identical to that of C1q from a normal calf. Gel-filtration of serum from dermatosparactic calf, on Sepharose 6B, showed the presence of C1q-antigenic material at only one position which was identical to the elution position of normal bovine C1q. No differdence, under dissociating conditions, could be seen in the size of the chains of C1q in specific immunoprecipitates isolated from the sera of dermatosparactic and normal animals, as judged by polyacrylamidegel electrophoresis (PAGE) in the presence of sodium dodecyl sulfate (SDS). The C1q from the dermatosparactic animal showed the same N-terminal amino acid and typtic-digest peptide pattern on HPLC as C1q from the normal calf. These results strongly suggest that pN-proteinase is not involved in the extracellular processing of C1q.     

On the appearance and role of a spacer group in the protein amino acids

Summary Of the 20 protein amino acids, 16 have a methylene group at the q145k04277077n8h/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> position, and a further three bear a methine group. No aromatic, carboxamido, carboxylic carbon, or hetero atoms are attached directly to the q145k04277077n8h/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> carbon, but they are separated by this methylene or occasionally by a longern-alkylene spacer group. Therefore, the structure of the protein amino acids should rather be formulated as H₂N–CH((CH₂)_n–Rq145k04277077n8h/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">)–COOH instead of the generally accepted H₂N–CH(R)–COOH. The appearance of and the role played by the spacer group are discussed in an evolutionary context. It is suggested that the spacer group appeared as a result of prebiotic selection, based on the relative abundance, racemization rate, and suitability for thermal polymerization of the protein amino acids and their homologs with various spacer group lengths. At the biotic level of evolution the requirements for ribosomal polymerization, as well as the abilities of polypeptides to maintain a stable and flexible threedimensional structure and to bind ligands are considered and are proposed to have been responsible for the possible exclusion of longer spacer groups. It is concluded that the general role of the spacer group is to ensure the uniformity of the constant regions H₂N–CH(-)–COOH and the individuality of the Rq145k04277077n8h/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0"> contact groups by spatially separating them.