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91.
Triple-helix formation of the peptide (Pro-Hyp-Gly)10 was monitored by nmr and CD spectroscopy. The two-dimensional nmr spectra indicated that the Gly C alpha H and Pro C delta H proton resonances shift upfield in going from the nonhelical to helical form, while hydroxy-proline resonances are unchanged. The integrated areas of the helical and nonhelical resonances could be monitored in the one-dimensional nmr spectrum, and indicate that in the (Pro-Hyp-Gly)10 about 90% of the residues are in a defined triple-helical conformation. The introduction of a glycine to alanine substitution or the deletion of a single hydroxyproline residue in the stable triple-helical peptide (Pro-Hyp-Gly)10 still allows trimers to be formed, but the trimers show a substantial loss of triple helix and decreased thermal stability compared with (Pro-Hyp-Gly)10. Two computer models were generated for the Gly----Ala peptide, one with the Ala side chains packed inside the helix and the other with the region containing the alanines forming a beta-bend that loops out from the helix. The nmr data is more consistent with the latter model. 相似文献
92.
Gomes Helga Do R.; Goes Joaquim I.; Parulekar A.H. 《Journal of plankton research》1992,14(9):1307-1329
This study examines the spatial distribution and size structureof phytoplankton biomass and productivity in relation to thevertical structrure of the Andaman Sea (northeastern IndianOcean). This region was characterized by low concentrationsof nutrients and high levels of insolation. Nitrogen availabilityappeared to control overall productivity with nitrate-basednew production accounting for 824% of thetotal primary production. Euphotic column chlorophyll (chl a)averaged 52.5 mg m2 of which a major portion was locatedas a subsurface chl a maximum (SCM) at 相似文献
93.
Shu-Mei Jiang Long Zhang Jun Hu Rui Shi Guang-He Zhou Yu-Hong Chen Wei-Bo Yin Richard R-C Wang Zan-Min Hu 《Génome》2004,47(6):1114-1121
The alien addition line TAI-27 contains a pair of chromosomes of Thinopyrum intermedium that carry resistance against barley yellow dwarf virus (BYDV). A subtractive library was constructed using the leaves of TAI-27, which were infected by Schizaphis graminum carrying the GAV strain of BYDV, and the control at the three-leaf stage. Nine differentially expressed genes were identified from 100 randomly picked clones and sequenced. Two of the nine clones were highly homologous with known genes. Of the remaining seven cDNA clones, five clones matched with known expressed sequence tag (EST) sequences from wheat and (or) barley whereas the other two clones were unknown. Five of the nine differentially expressed sequences (WTJ9, WTJ11, WTJ15, WTJ19, and WTJ32) were highly homologous (identities >94%) with ESTs from wheat or barley challenged with pathogens. These five sequences and another one (WTJ18) were also highly homologous (identities >86%) with abiotic stress induced ESTs in wheat or barley. Reverse Northern hybridization showed that seven of the nine differentially expressed cDNA sequences hybridized with cDNA of T. intermedium infected by BYDV. Three of these also hybridized with cDNA of line 3B-2 (a parent of TAI-27) infected by BYDV. The alien chromosome in TAI-27 was microdissected. The second round linker adaptor mediated PCR products of the alien chromosomal DNA were labeled with digoxygenin and used as the probe to hybridize with the nine differentially expressed genes. The analysis showed that seven differentially expressed genes were homologous with the alien chromosome of TAI-27. These seven differentially expressed sequences could be used as ESTs of the alien chromosome of TAI-27. This research laid the foundation for screening and cloning of new specific functional genes conferring resistance to BYDV and probably other pathogens. 相似文献
94.
Summary Using a combinatorial peptide library method, we identified YIYGSFK as an efficient and specific peptide substrate for pp60c-src protein tyrosine kinase (PTK) [Lam et al., Int. J. Pept. Protein Res., 45 (1995) 587]. Employing YIYGSFK as a template, we synthesized and evaluated a series of pseudosubstrate-based inhibitors for pp60c-src. We found that the efficiency of a given inhibitor was highly dependent on the specific tyrosine analog used at the phosphorylation site of the substrate. One of these pseudosubstrate inhibitors, YI(2-Nal)GSFK, selectively inhibited the kinase activity of pp60c-src, with a Ki of 24 M. This peptide inhibitor exhibited selectivity for pp60c-src as compared to other PTKs tested, such as c-Abl and Bcr-Abl. Our results suggest that selective inhibitors for a specific PTK can be developed when the structure of a specific and efficient small peptide substrate for this PTK can be used as a template for structure modification.Abbreviations 1-Nal
l-1-naphthylalanine
- 2-Nal
l-2-naphthylalanine
- BOP
benzotriazolyl-N-oxy-tris(dimethylamino)-phosphonium hexafluorophosphate
- BSA
bovine serum albumin
- cAPK
cyclic AMP-dependent protein kinase
- DIEA
diisopropylethylamine
- EGFR
epidermal growth factor receptor
- Fmoc
fluorenylmethoxycarbonyl
- HOBt
1-hydroxybenzotriazole
- MES
2-[N-morpholino]ethanesulfonic acid
- PBS
phosphate-buffered salts
- pCl
l-p-chlorophenylalanine
- pF
l-p-fluorophenylalanine
- PTK
protein tyrosine kinase
- TLC
thin-layer chromatography 相似文献
95.
本文以临床体征,胸片和连续二次以上细菌培养阳性为诊断标准,报告革兰阴性杆菌肺炎23例,并就其临床表现,并发症及预后进行分析,提出8种情况应考虑革兰阴性杆菌肺炎,对临床诊断和治疗有指导意义. 相似文献
96.
97.
A link between increased transforming activity of lymphoma-derived MYC mutant alleles, their defective regulation by p107, and altered phosphorylation of the c-Myc transactivation domain. 总被引:5,自引:4,他引:1 下载免费PDF全文
A T Hoang B Lutterbach B C Lewis T Yano T Y Chou J F Barrett M Raffeld S R Hann C V Dang 《Molecular and cellular biology》1995,15(8):4031-4042
98.
S-Nitrosoglutathione in Rat Cerebellum: Identification and Quantification by Liquid Chromatography-Mass Spectrometry 总被引:1,自引:0,他引:1
Ina Kluge Ursula Gutteck-Amsler Markus Zollinger Kim Quang Do 《Journal of neurochemistry》1997,69(6):2599-2607
Abstract: Given the extreme lability and the facile inactivation of the messenger nitric oxide (NO) by many reactive biochemical species, it has been suggested that some intermediate compounds, for example, S -nitrosothiols, may act to stabilize NO and at the same time to preserve its biological activity. To test this hypothesis, we investigated if the S -nitrosothiol of glutathione, which is the predominant low molecular weight thiol in CNS, is present in the rat brain. The HPLC analysis of cerebellar extract from [35 S]cysteine-prelabeled slices suggested that S -nitrosoglutathione (GSNO) was indeed present in rat brain. To detect endogenous GSNO, a methodology based on liquid chromatography-mass spectrometry was developed. Besides an unequivocal identification of the endogenous GSNO, this method also permitted its precise quantification using 15 N-labeled GSNO ([15 N]-GSNO) as internal standard. GSNO level in adult cerebellum amounts to 15.4 ± 1.4 pmol/mg of protein. This is the first direct demonstration of the presence of endogenous GSNO in CNS. The packaging of NO in the form of GSNO might serve to facilitate its transport, prolong its life, and target its delivery to specific effectors. 相似文献
99.
Somatic embryos and adventitious shoots were initiated from immature cotyledons 10–14 weeks after anthesis. Maximum embryogenesis occurred 12 weeks after anthesis and maximum shoot organogenesis occurred 14 weeks after anthesis. The best treatment for induction of somatic embryos and adventitious shoots from immature cotyledon explants was on agar-solidified WPM supplemented with 0.1 M 2,4-D and 5.0 M TDZ and incubated in light for the first four weeks. Rooting of adventitious shoots was best if they were quickdipped in 2.5 mM IBA and 1.25 mM NAA in 1% dimethyl formamide and 3.9% ethanol (120 Wood's Rooting Compound: water, by volume). Plantlets from rooted adventitious shoots were acclimatized to the greenhouse.Abbreviations BA
Benzyladenine
- 2,4-D
2,4-dichlorophenoxyacetic acid
- DKW
Driver and Kuniyuki (1984) walnut medium
- IBA
indolebutyric acid
- LP
Long and Preece medium described herein
- NAA
naphthaleneacetic acid
- PPF
photosynthetic photon flux
- TDZ
thidiazuron
- WPM
Woody Plant Medium of Lloyd and McCown (1980) 相似文献
100.
Summary Single and multiple Clostridium acetobutylicum P262 sporulation, clostridial stage, granulose, capsule and solvent producing mutants were isolated. Although common regulatory components were involved in the regulation of these events, each individual pathway was able to function independently of each other. Inhibitors of DNA replication inhibited spore formation but did not affect solvent, clostridial stage, granulose and capsule production. 相似文献