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1.
Wounding Inhibits Protein Synthesis yet Stimulates Polysome Formation in Aged, Excised Pea Epicotyls 总被引:2,自引:0,他引:2
Wounding of aged, previously-excised pea epicotyl segments byremoval of the basal 12 mm resulted in a rapid (beginningwithin 15 min) recruitment of monosomes on to polysomes andan even more rapid (maximal between 612 min) inhibitionof protein synthesis in the remaining tissue. This inhibitionof protein synthesis in vivo did not appear to be an artefactcaused by the removal of highly active tissue (e.g., callus,contaminating bacteria), since wounds inflicted at a site distantfrom the region analyzed still elicited the response, and proteinsynthesis in the 12 mm slices (normally discarded) wasinhibited even more strongly than it was in the remaining tissue.The proportion of radioactive methionine in nascent chains (boundto polysomes) increased, while the production of completed polypeptidesdecreased, after wounding. Cycloheximide, a known inhibitorof the ribosome translocation/release process mimicked someof the effects of wounding. We interpret the results to indicatethat the initial effect of wounding is to inhibit translationby inhibiting the ribosome translocation/release process, whereasthe subsequent recovery in protein synthesis is brought aboutpartly by a recovery in ribosome translocation/release and partlyby enhanced initiation.
1 Present address: Harvard-MIT Division of Health Science andTechnology, MIT, Cambridge, Massachusetts 02139, U.S.A.
2 Present address: Institute of Agricultural Environment Control,College of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama790, Japan. (Received May 26, 1986; Accepted August 4, 1986) 相似文献
2.
Corpora lutea removed from pregnant hamster deprived of endogenous luteinizing hormone for varying periods were compared for
their responsiveness to externally added luteinizing hormone. The corpora lutea removed on the 8th day of pregnancy exhibited
a dose-dependent increase in progesterone production in response to added luteinizing hormone upto a concentration of 2.5
Μg/ml. The total progesterone synthesised by the corpora lutea decreased with increase in the duration ofin vivo luteinizing hormone deprivation. However, the hormone deprivation had to be for a minimum period of 24 h before a marked
reduction in thein vitro responsiveness could be seen. Neutralisation of endogenous luteinizing hormone increased the luteal cholesterol ester concentration,
whilein vitro incubation of such tissue with luteinizing hormone resulted in a marked reduction in cholesterol ester levels. Corpora lutea
removed from hamsters on day 8, 15 and 16 of pregnancy when compared for their responsivenessin vitro to added luteinizing hormone showed that the luteal tissue of day 8 produced more progesterone relative to those of day 15/16.
In contrast, depletion of free and esterified cholesterol increased with the increase in age of corpora lutea (from 15% on
day 8 to 67% on day 16). 相似文献
3.
RNA binding proteins play significant roles in many bio-macromolecular systems. Aromatic amino acid residues are vital for several biological functions. In the present work, the influences of π–π interactions in RNA binding proteins are analyzed. There are a total of 3,396 π-residues in RNA binding proteins out of which 1,547, 1,241, and 608 are phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp), respectively. Among these 945, 634, and 356 Phe, Tyr, and Trp residues, respectively, are involved in π–π interactions. The observations indicate that majority of the aromatic residues in RNA binding proteins are involved in π–π interactions. Side chain–side chain π–π interactions are the predominant type of interactions in RNA binding proteins. These π–π interactions stabilize the core regions within RNA binding proteins. π–π interacting residues are evolutionary conserved. Residue-wise analysis indicates that π–π interacting residues have higher long-range contacts and hence they are important in the global conformational stability of these proteins. 相似文献
4.
β-lactam group of antibiotics is the most widely used therapeutic molecules for treating bacterial infections. The main mode of bacterial resistance to β-lactams is by β-lactamases. In the present study, we report our results on the role of cation–π interactions in β-lactamases and their environmental preferences. The number of interactions formed by arginine is higher than lysine in the cationic group, while tyrosine is comparatively higher than phenylalanine and tryptophan in the π group. Our results indicate that cation–π interactions might play an important role in the global conformational stability of β-lactamases. 相似文献
5.
ABSTRACTFT-IR and FT-Raman spectra of 2,2′-bipyridine-3,3′-dicarboxylic acid (B3DA), 2,2′-bipyridine-4,4′-dicarboxylic acid (B4DA) and 2,2′-bipyridine-5,5′-dicarboxylic acid (B5DA) were recorded and analysed. The quantum chemical calculations of the title compounds begin with barrier potentials at different rotation angles around the C–C′ and C–Cα bonds in order to arrive conformation of lowest energy using DFT employing B3LYP functional with 6-311++G(d,p) basis set. This confirmation was further optimised to get the global minimum geometry. The vibrational frequencies along with IR, Raman intensities were computed, the rms error between observed and calculated frequencies were 11.2 cm?1, 10.2 cm?1 and 12.2 cm?1 for B3DA, B4DA, and B5DA. An 87-element modified valence force field is derived by solving the inverse vibrational problem using Wilson’s GF matrix method. This force field is refined using 163 observed fundamentals employing in overlay least-squares technique. The average error between computed and experimental frequencies was found as 12.85 cm?1 using potential energy distribution (PED) and eigenvectors. By using the gauge-independent atomic orbital (GIAO) method calculate the 1H and 13C NMR chemical shifts of the molecules and compared with experimental results. The first-order hyperpolarisability, HOMO and LUMO energies, molecular electrostatic potential (MESP) and natural orbital analysis (NBO) of titled compounds were evaluated using DFT. 相似文献
6.
Chundi Vinay Kumar Rayapadi G. Swetha Sudha Ramaiah 《Journal of biomolecular structure & dynamics》2013,31(8):1695-1709
Mutations in the gene-encoding vesicle lipopolysaccharide-induced tumor necrosis factor (LITAF) protein cause Charcot–Marie–Tooth type 1C (CMT1C) disease, a neurological disorder. The LITAF gene is mapped to chromosome number 16 and can be found at cytogenetic location 16p13 of the chromosome. CMT1C-linked small integral membrane protein of lysosome/late endosome mutants are loss-of-function mutants that act in a dominant negative manner to impair endosomal trafficking, leading to prolonged extracellular signal-regulated kinases 1/2 signaling downstream of ErbB activation. Mutation W116G in the LITAF decreases the stability of the protein and also interrupts the functioning of gene. We have analyzed the single nucleotide polymorphism (SNP) results of 28 nsSNPs obtained from dbSNP. We also carried out multiple molecular dynamics simulations of 200 ns and obtained results of root-mean-square deviation, root-mean-square fluctuation, radius of gyration, solvent-accessible surface area, H-bond, and principal component analysis to check and prove the stability of both the wild type and the mutant. The protein was then checked for its aggregation and the results showed loss of helix. The loss of helix leads to the instability of the protein. 相似文献
7.
Hameed Asif Shahina Mariyam Young Li-Sen Lai Wei-An Sridhar Kandikere Ramaiah Young Chiu-Chung 《Plant and Soil》2019,443(1-2):73-86
Plant and Soil - To screen plant-associated Burkholderia strains for plant probiotic traits including allelochemical metabolism and understand their role on rice allelopathy using a... 相似文献
8.
The economic burden of lymphatic filariasis in India 总被引:11,自引:0,他引:11
Lymphatic filariasis affects 119 million people living in 73 countries, with India accounting for 40% of the global prevalence of infection. Despite its debilitating effects, lymphatic filariasis is given very low control priority. One of the reasons for this is paucity of information on the economic burden of the disease. Recent studies in rural areas of south India have shown that the treatment costs and loss of work time due to the disease are considerable. Based on the results of these studies, Kapa Ramaiah et al. here estimate the annual economic loss because of lymphatic filariasis for India and discuss the implications of their findings. 相似文献
9.
Wagh S Ramaiah A Subramanian R Govindarajan R 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》2000,13(6):442-448
In melanocytes, enzymes involved in the generation of melanin monomers are present and active in coated vesicles which are known to be acidic. Melanin polymerization however, occurs only in melanosomes. In vitro, it is not possible to generate melanin at the acidic pH of melanosomes using 3,4-dihydroxyphenylalanine (DOPA) and tyrosinase alone whereas melanin readily forms at higher pH with these reagents. Dimerization and elongation of the melanin polymer is known to require deprotonation. We have hypothesized that the amino acid side chains of melanosomal proteins act as proton acceptors to initiate polymerization and that the protonated basic groups serve to attract the negatively charged oligomers thus aiding polymerization and binding to proteins. We show that basic model proteins and basic premelanosomal proteins promote polymerization at an acidic pH and that positively charged surfaces allow binding of the growing melanin polymer. With progressive polymerization and exhaustion of the proton abstracting ability of melanosomal proteins, melanosomal pH drops further, which, we argue, is an additional controlling step that limits tyrosinase activity and melanin polymerization. 相似文献
10.
Sudhakar A Ramachandran A Ghosh S Hasnain SE Kaufman RJ Ramaiah KV 《Biochemistry》2000,39(42):12929-12938
Phosphorylation of serine 51 residue on the alpha-subunit of eukaryotic initiation factor 2 (eIF2alpha) inhibits the guanine nucleotide exchange (GNE) activity of eIF2B, presumably, by forming a tight complex with eIF2B. Inhibition of the GNE activity of eIF2B leads to impairment in eIF2 recycling and protein synthesis. We have partially purified the wild-type (wt) and mutants of eIF2alpha in which the serine 51 residue was replaced with alanine (51A mutant) or aspartic acid (51D mutant) in the baculovirus system. Analysis of these mutants has provided novel insight into the role of 51 serine in the interaction between eIF2 and eIF2B. Neither mutant was phosphorylated in vitro. Both mutants decreased eIF2alpha phosphorylation occurring in hemin and poly(IC)-treated reticulocyte lysates due to the activation of double-stranded RNA-dependent protein kinase (PKR). However, addition of 51D, but not 51A mutant eIF2alpha protein promoted inhibition of the GNE activity of eIF2B in hemin-supplemented rabbit reticulocyte lysates in which relatively little or no endogenous eIF2alpha phosphorylation occurred. The 51D mutant enhanced the inhibition in GNE activity of eIF2B that occurred in hemin and poly(IC)-treated reticulocyte lysates where PKR is active. Our results show that the increased interaction between eIF2 and eIF2B protein, occurring in reticulocyte lysates due to increased eIF2alpha phosphorylation, is decreased significantly by the addition of mutant 51A protein but not 51D. Consistent with the idea that mutant 51D protein behaves like a phosphorylated eIF2alpha, addition of this partially purified recombinant subunit, but not 51A or wt eIF2alpha, increases the interaction between eIF2 and 2B proteins in actively translating hemin-supplemented lysates. These findings support the idea that phosphorylation of the serine 51 residue in eIF2alpha promotes complex formation between eIF2alpha(P) and eIF2B and thereby inhibits the GNE activity of eIF2B. 相似文献