Conformational changes in ovalbumin at acid pH

Several physicochemical parameters of ovalbumin were examined at acid pH. The intrinsic viscosity and far UV-CD spectrum at pH 2 did not differ from those at pH 7. But the near UV-CD spectrum, difference absorption spectrum around 250-320 nm, and fluorescence spectrum showed micro-environmental changes around the aromatic amino acid residues in acid solution. The reactivity of one of the four sulfhydryl groups with 2,2'-dithiodipyridine increased at pH below 5. The rate of denaturation by urea and that of surface tension decay were high in the low pH range. We concluded that at low pH (around 2), ovalbumin molecules kept their native globular conformation, but that their chain flexibility increased and they were very susceptible to denaturation. This state might be equivalent to the molten-globule state observed with some globular proteins in acidic region.     

Reactions of the aminoacyl-tRNA synthetase-aminoacyl adenylate complex and amino acid derivatives. A new approach to peptide synthesis

Several kinds of dipeptide derivative were shown to be formed by the reactions of the aminoacyl adenylate-aminoacyl-tRNA synthetase complex and amino acid ester or amide. It was shown that the peptide bond could be formed by aminoacyl-tRNA synthetases even in the absence of the ribosome.     

Location of Lyb-2 on mouse chromosome 4

TheLyb-2 locus responsible for the B-lymphocyte alloantigen system Lyb-2 is located on chromosome 4 at a distance of 20.6±4.9 map units fromPgm-2. A three-point cross indicated the orderLyb-2: Mup-1b Pgm-2.     

Freezing denaturation of ovalbumin at acid pH

The effects of rapid freezing and thawing at acid pH on the physiochemical properties of ovalbumin were examined. At low pH (around 2), UV difference spectra showed microenvironmental changes around the aromatic amino acid residues; elution curves by gel permeation chromatography showed decreasing numbers of monomers after neutralization. These changes depended on the incubation temperature (between -196 and -10 degrees C) and the protein concentration (0.5-10 mg/ml), and a low concentration of ovalbumin incubated at around -40 degrees C suffered the most damage to its conformation. With freezing and then incubation at -40 degrees C, three of the four sulfhydryl groups in the ovalbumin molecule reacted with 2,2'-dithiodipyridine. The CD spectra showed these changes in the secondary structure, but they were smaller than those when guanidine hydrochloride was used for denaturation. Supercooling at -15 degrees C or freezing at -196 degrees C had little or no effect on the conformation of the ovalbumin molecule. Thus, irreversible conformational changes of ovalbumin were caused under the critical freezing condition at an acid pH. These changes arose from partial denaturation and resembled those with thermal denaturation of ovalbumin at neutral pH.     

Two ANGUSTIFOLIA genes regulate gametophore and sporophyte development in Physcomitrella patens

In Arabidopsis thaliana the ANGUSTIFOLIA (AN) gene regulates the width of leaves by controlling the diffuse growth of leaf cells in the medio‐lateral direction. In the genome of the moss Physcomitrella patens, we found two normal ANs (PpAN1‐1 and 1‐2). Both PpAN1 genes complemented the A. thaliana an‐1 mutant phenotypes. An analysis of spatiotemporal promoter activity of each PpAN1 gene, using transgenic lines that contained each PpAN1‐promoter– uidA (GUS) gene, showed that both promoters are mainly active in the stems of haploid gametophores and in the middle to basal region of the young sporophyte that develops into the seta and foot. Analyses of the knockout lines for PpAN1‐1 and PpAN1‐2 genes suggested that these genes have partially redundant functions and regulate gametophore height by controlling diffuse cell growth in gametophore stems. In addition, the seta and foot were shorter and thicker in diploid sporophytes, suggesting that cell elongation was reduced in the longitudinal direction, whereas no defects were detected in tip‐growing protonemata. These results indicate that both PpAN1 genes in P. patens function in diffuse growth of the haploid and diploid generations but not in tip growth. To visualize microtubule distribution in gametophore cells of P. patens, transformed lines expressing P. patens α‐tubulin fused to sGFP were generated. Contrary to expectations, the orientation of microtubules in the tips of gametophores in the PpAN1‐1/1‐2 double‐knockout lines was unchanged. The relationships among diffuse cell growth, cortical microtubules and AN proteins are discussed.     

Secreted Frizzled-Related Protein 3 Regulates Activity-Dependent Adult Hippocampal Neurogenesis

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Highlights? Wnt inhibitor sFRP3 exhibits activity-dependent expression in the adult hippocampus ? sFRP3 maintains quiescence of adult hippocampal radial glia-like neural stem cells ? sFRP3 inhibits maturation, dendritic development, and spinal formation of new neurons ? sFRP3 partially mediates activity-dependent adult hippocampal neurogenesis     

Facile Diastereoseparation of Glycosyl Sulfoxides by Chiral Stationary Phase

Separation of the diastereomers of glycosyl sulfoxides differing in the sulfur chirality has been difficult. This article presents a fast and scalable method for their diastereoseparation using a chiral stationary phase. The usefulness of this method was demonstrated in a 500‐mg scale separation within 20 min, and in the separation of trisaccharyl sulfoxide diastereomers. Chirality 28:534–539, 2016. © 2016 Wiley Periodicals, Inc.     

Properties of blocking and non-blocking monoclonal antibodies specific for human macrophage galactose-type C-type lectin (MGL/ClecSF10A/CD301)

Monoclonal antibodies (mAbs) specific for the human macrophage galactose-type calcium-type lectin (MGL) were established. The recombinant extracellular domain of MGL was used to immunize a mouse, and 10 hybridoma clones were obtained. Binding of recombinant MGL to asialo-bovine submaxillary mucin was shown to be blocked by mAbs MLD-1, 4 and 6. Immunoprecipitation of MGL from lysates of COS-1 cells transfected with MGL cDNA (form 6A) was achieved with mAbs MLD-1, 4, 7, 8 and 16. Chimeric recombinant proteins between human MGL and mouse MGL1 were used to determine the location of the epitopes for these mAbs. mAbs MLD-8, 13, 15 and 16 interacted with the amino terminal side of the conserved WVDGTD sequence immediately upstream of QPD, whereas mAbs MLD-7, 12 and 17 interacted with the other side. mAbs MLD-1, 4, and 6 apparently required both sides of this boundary. mAbs MLD-15 and 16 were shown to recognize the protein products of alternatively spliced mRNA 6A/8A and 6C/8A, having deletions at the boundary of exons 7 and 8, in addition to full length and other spliced forms of MGL (6A, 6B and 6C), whereas the other mAbs bound only full length and forms 6A, 6B and 6C.     

Threshold-dependent DNA synthesis by pure pressure in human aortic smooth muscle cells: Gialpha-dependent and -independent pathways

Mechanical forces related to pressure and flow are important for the etiology of atherosclerosis and hypertension. We hypothesized the presence of mechanosensors that were solely sensitive to pure atmospheric pressure in the absence of shear and tensile stresses. A pressure-loading apparatus was set up to examine the effects of atmospheric pressure on human aortic smooth muscle cells (HASMC). Pressure application of 140 to 180 mmHg produced DNA synthesis in a pressure-dependent manner. In contrast, pressure of 120 mmHg or less produced no significant change. Both extracellular signal-regulated kinase and c-Jun N-terminal kinase activities, but not p38 activity, were stimulated by pressures of more than 160 mmHg. Pertussis toxin (PTx) completely inhibited the pressure-induced increase of DNA synthesis under the high pressure of 200 mmHg. These data suggest that HASMC have a mechanosensing cellular switch for DNA synthesis which is sensitive to pure atmospheric pressure, and that the molecular switch is activated by pressure of more than 140 mmHg. The activation mechanism consists of PTx-sensitive and -insensitive pathways, and the former is activated by high pure pressure.