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Polynucleotide analogues. XIV. Poly N2-dimethylguanylate 总被引:2,自引:0,他引:2
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Polynucleotide analogues. VIII. Poly 3-isoadenylic acid 总被引:2,自引:0,他引:2
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Poly(Aspartic Acid) Degradation by a Sphingomonas sp. Isolated from Freshwater 总被引:2,自引:0,他引:2
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Kenji Tabata Ken-Ichi Kasuya Hideki Abe Kozue Masuda Yoshiharu Doi 《Applied microbiology》1999,65(9):4268-4270
A poly(aspartic acid) degrading bacterium (strain KT-1 [JCM10459]) was isolated from river water and identified as a member of the genus Sphingomonas. The isolate degraded only poly(aspartic acid)s of low molecular masses (<5 kDa), while the cell extract hydrolyzed high-molecular-mass poly(aspartic acid)s of 5 to 150 kDa to yield aspartic acid monomer. 相似文献
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The solution characterization of poly(Lys-Ala-Glu) is described. This polytripeptide is zwitterionic at neutral pH and is shown to take on a conformation which is dictated by the state of ionization, molecular weight, temperature, and solvent. The polypeptide is almost entirely α-helical at low pH and temperature for polymers of greater than 25,000 molecular weight. Melting profiles for these conditions show tm ~ 20°C. Analysis of circular dichroism curves shows the α-helical content to vary in a linear manner with molecular weight in the range 3000–30,000. At neutral pH the charged polypeptide is essentially random, but substantial α-helix could be induced by addition of methanol or trifluoroethanol. At temperatures where the sequential polypeptide is a random coil, addition of trifluoroethanol produces a polymer which is mostly α-helical but also contains an appreciable ammount of β-structure. The infrared spectrum of a low-molecular-weight fraction assumed to be cyclo(Lys-Ala-Glu)2 was tentatively assigned a β-pleated sheet structure. A comparison of this polytripeptide in various ionization states with other polytripeptides containing L -alanine and L -glutamate or L -lysine shows the α-helix directing properties for the (uncharged) residues to lie in the order Ala > Glu > Lys. 相似文献
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Fernandez-Castillo R Rodriguez-Valera F Gonzalez-Ramos J Ruiz-Berraquero F 《Applied and environmental microbiology》1986,52(1):214-216
Bacillus cereus, Clostridium perfringens, Staphylococcus aureus, Pseudomonas fluorescens, Pseudomonas fragi, Escherichia coli, and Salmonella "anatum" were challenged with butylated hydroxyanisole (BHA). Susceptibility was measured as the concentration of BHA required to cause a 90% reduction in bacterial survivors. Staphylococcus aureus LP and P. fragi were two of the most resistant species examined; C. perfringens and P. fluorescens were the most susceptible. Gram stain reaction was found not to be a strict indicator of bacterial susceptibility to BHA. There was no obvious relationship between individual fatty acids and susceptibility. The ratio of saturated to unsaturated fatty acids in the total lipid fraction of only the gram-positive species was related to susceptibility. The ratios of saturated to unsaturated fatty acids of other fractions were not related to susceptibility. 相似文献
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Poly(l-lactide) degradation by Kibdelosporangium aridum 总被引:3,自引:0,他引:3
A new poly(L-lactide) (PLA)-degrading actinomycete, Kibdelosporangium aridum, degraded more than 97 mg out of 100 mg added high molecular weight PLA film (Mn: 3.4 x 10(5)) within 14 d in liquid culture. L-Lactic acid, the monomeric degradation product of PLA, was totally assimilated by the strain. In solid culture, many distinct grooves formed by the morphology of filamentous microorganisms on the surface of a PLA film were observed by scanning electron microscopy. 相似文献
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Poly(L-lactide) degradation by Saccharothrix waywayandensis 总被引:1,自引:0,他引:1
Poly(l-lactide) (PLA) was degraded by more than 95 mg from 100 mg PLA film by an actinomycete, Saccharothrix waywayandensis, growing in 100 ml liquid culture containing 0.1% (w/v) gelatin. In addition to degrading PLA, this strain assimilated the major degradation product of PLA, l-lactic acid. 相似文献
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S Sorscher J Lillienau J L Meinkoth J H Steinbach C D Schteingart J Feramisco A F Hofmann 《Biochemical and biophysical research communications》1992,186(3):1455-1462
Apical membranes of ileal enterocytes contain the major Na+/bile acid cotransporter activity in mammals. Microinjection of guinea pig ileal mucosal Poly A+ mRNA (25 ng) into Xenopus oocytes resulted in 22,23-3H-cholyltaurine uptake at day 3 after injection (453 fmol/oocyte-hr), while control viral mRNA (25 ng) gave an uptake rate of 133 fmol/oocyte-hr. The transport rate increased in direct relationship to the concentration of injected mRNA, cholyltaurine, or Na+ in the incubation media. Uptake of cholyltaurine using rabbit ileal mucosal Poly A+ mRNA was 3891 fmole/oocyte-hr compared to rabbit jejunal-mucosa Poly A+ mRNA (control) injections inducing 728 fmol/oocyte-hr. Such expression of the ileal Na+/bile acid cotransporter may facilitate cloning of this key mammalian gene. 相似文献
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The content and size of the poly(A) on Mengovirus RNA grown in both mouse L cells and HeLa cells have been examined. Virion RNA from either cell line could bind to poly(U) filters and contained RNase-resistant stretches of poly(A) which could be analyzed by electrophoresis in polyacrylamide gels. The size of the poly(A) on the Mengovirus RNA was independent of the host cell and averaged from 50 to 70 nucleotides. 相似文献
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Poly(ADP-ribosylation) and genomic stability. 总被引:5,自引:0,他引:5
Poly(ADP-ribose) polymerases (PARPs) catalyze the synthesis of ADP-ribose polymers and attach them to specific target proteins. To date, 6 members of this protein family in humans have been characterized. The best-known PARP, PARP-1, is located within the nucleus and has a major function in DNA repair but also in the execution of cell death pathways. Other PARP enzymes appear to carry out highly specific functions. Most prominently, the tankyrases modify telomere-binding proteins and thereby regulate telomere maintenance. Since only a single enzyme, poly(ADP-ribose) glycohydrolase (PARG), has been identified, which degrades poly(ADP-ribose), it is expected that this protein has important roles in PARP-mediated regulatory processes. This review summarizes recent observations indicating that poly(ADP-ribosylation) represents a major mechanism to regulate genomic stability both when DNA is damaged by exogenous agents and during cell division. 相似文献
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When poly(ethylene glycol) 3350 is estimated by the method of Skoog [(1979) Vox Sang. 37, 345-349], fine particles form. The particles are not attributable to residual protein but to a poly(ethylene glycol)/barium/iodine complex that can be quantitated by means of a laser nephelometer. The method is sensitive to at least 10 mg% poly(ethylene glycol) 3350 (4 micrograms in the cuvette) in 2500 mg% protein, and nephelometer response is approximately linear between 30 and 200 mg% of the polymer. The coefficient of variance is about 8%. Triton X-100, Pluronic F-68, Varonic 1000MS, and poly(ethylene glycol) of higher and lower molecular weight react well. Alkylated celluloses, dextrans, glycerol, glycine, and sodium dodecyl sulfate do not react significantly. Barium can be replaced with Mg, Ca, Ni, Fe, and other divalent cations in the reaction, but other than for Hg, light-scattering is most intense with Ba. The reaction goes to completion in about 5 min and is most intense when the barium is added before the iodine. 相似文献
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Alemasova Elizaveta E. Naumenko Konstantin N. Sukhanova Maria V. Lavrik Olga I. 《Biochemistry. Biokhimii?a》2022,87(1):S32-S47
Biochemistry (Moscow) - Poly(ADP-ribosyl)ation is a post-translational modification of proteins that performs an essential regulatory function in the cellular response to DNA damage. The key enzyme... 相似文献
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Poly(glutamic acid) for biomedical applications. 总被引:4,自引:0,他引:4
Paclitaxel is a widely used anti-cancer agent. Conjugates of paclitaxel with poly(glutamic acid) have shown great promise in preclinical trials, and clinical trials are now underway. Preclinical data suggest that more paclitaxel is preferentially delivered to tumor sites vs. nonconjugated paclitaxel. When poly(glutamic acid) is conjugated to other families of cancer drugs, similar improvements in effectiveness and reduced toxicity are observed. Optimization of poly(glutamic acid) for use in drug delivery applications is a key step in making this technology viable. 相似文献
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The helix–coil transition in poly(γ-benzyl L -glutamate-co-γ-methyl L -glutamate) copolypeptides was studied experimentally in nonaqueous solvents and the results compared with theory. It is found that the transition can be described by the same theory as for the homopolypeptides, but the corresponding parameters are not related in the expected way to those of the homopolymers, due to the effect of the side chains on the stability of the helix, which is not taken into account explicitly by the theory. 相似文献