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991.
Diketopinic acid has been synthesized and shown to be a reagent of choice for specific, reversible modification of the guanidine
groups of arginine residues. Diketopinic acid is a yellow crystalline substance and the carboxyl group of the reagent is a
convenient handle for attachment to other molecules. The adducts of diketopinoyl derivatives with the guanidine group are
cleaved by 0.2 M o-phenylenediamine at pH 8–9. The modification and regeneration of arginine and of arginyl residues in soyabean
trypsin inhibitor and insulin are presented as demonstrations of the use of the reagent. The use of diketopinoyl resin in
the separation of oxidized A and B chains of insulin has been discussed.
Presented in part at the Ninth American Peptide symposium 1985, Toronto, Canada. 相似文献
992.
993.
The mating-type locus of Neurospora crassa regulates mating identity and entry into the sexual cycle. The mat A idiomorph encodes three genes, mat A-1, mat A-2, and mat A-3. Mutations in mat A-1 result in strains that have lost mating identity and vegetative incompatibility with mat a strains. A strain containing mutations in both mat A-2 and mat A-3 is able to mate, but forms few ascospores. In this study, we describe the isolation and characterization of a mutant deleted for mat (deltamatA), as well as mutants in either mat A-2 or mat A-3. The deltamatA strain is morphologically wild type during vegetative growth, but it is sterile and heterokaryon compatible with both mat A and mat a strains. The mat A-2 and mat A-3 mutants are also normal during vegetative growth, mate as a mat A strain, and produce abundant biparental asci in crosses with mat a, and are thus indistinguishable from a wild-type mat A strain. These data and the fact that the mat A-2 mat A-3 double mutant makes few asci with ascospores indicate that MAT A-2 and MAT A-3 are redundant and may function in the same pathway. Analysis of the expression of two genes (sdv-1 and sdv-4) in the various mat mutants suggests that the mat A polypeptides function in concert to regulate the expression of some sexual development genes. 相似文献
994.
F. T. Rantin A. L. Kalinin M. L. Glass † M. N. Fernandes 《Journal of fish biology》1992,41(5):805-812
Predominantly, Hoplias malabaricus inhabits stagnant O2 poor environments, whereas Hoplias lacerdae occurs in well-aerated streams. The present study evaluates the influence of mode of life on O2 uptake and gill ventilation in equally-sized (300 g) specimens of this genus at 25° C. Comparing the species, H. lacerdae was characterized by the highest O2 uptake and gill ventilation combined with a relatively higher cost of breathing and a lower O2 extraction. Both species substantially increased ventilation in response to hypoxia with the difference that H. malabaricus exclusively augmented tidal volume, whereas H. lacerdae also increased breathing frequency. 相似文献
995.
Attentional modulation of central odor processing 总被引:4,自引:1,他引:3
Two studies were conducted to investigate the influence of attention on the
components of the chemosensory event-related potential (CSERP). In the
first study the odors linalool and eugenol were delivered to six male
subjects, in the second study three male and two female subjects were
presented with their own body odor (axillary hair) and the body odor of a
same sex donor. In both studies the odors were presented in an oddball
paradigm under ignore and attend conditions via a constant- flow
olfactometer. In the ignore condition attention was diverted from the odors
with a distractor task, while in the attend condition the subjects were
asked to respond to the infrequently occurring odor. In both studies the
allocation of attention led to a decrease in the latency of the early
components (N1, P2, N2) and to an increase in the amplitude of the late
positivities. The modulation of the early components suggests that
attentional gating in olfaction might already be effective at an early
processing level.
相似文献
996.
ETO, a Target of t(8;21) in Acute Leukemia, Interacts with the N-CoR and mSin3 Corepressors 总被引:29,自引:7,他引:22
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997.
998.
Regulation of a putative high-affinity nitrate transporter (Nrt2;1At) in roots of Arabidopsis thaliana 总被引:10,自引:0,他引:10
Zhuo D Okamoto M Vidmar JJ Glass AD 《The Plant journal : for cell and molecular biology》1999,17(5):563-568
Putative high-affinity nitrate (NO3-) transporter genes, designated Nrt2;1At and Nrt2;2At, were isolated from Arabidopsis thaliana by RT-PCR using degenerate primers. The genes shared 86% and 89% identity at the amino acid and nucleotide levels, respectively, while their proteins shared 30-73% identities with other eukaryotic high-affinity NO3- transporters. Both genes were induced by NO3-, but Nrt2;1At gene expression was not apparent in 2- and 5-day-old plants. By 10 days, and thereafter, Nrt2;1At gene expression in roots was substantially higher than for the Nrt2;2At gene. Root Nrt2;1At expression levels were strongly correlated with inducible high-affinity 13NO3- influx into intact roots under several treatment conditions. The use of inhibitors of N assimilation indicated that downregulation of Nrt2;1At expression was mediated by NH4+, gln and other amino acids. 相似文献
999.
Blevitt JM Früh K Glass C Jackson MR Peterson PA Huang S 《Journal of biomolecular screening》1999,4(2):87-91
The transporter associated with antigen processing (TAP) is essential for antigen presentation by major histocompatibility complex (MHC) class I molecules. Traditional methods used to analyze peptide transport mediated by TAP require radioactive labeling of peptides and time-consuming manipulation of Concanavalin A-Sepharose. Drug discovery research requires rapid and reliable evaluation of large number of samples for bioactivity. To meet these requirements a nonradioactive, HTS assay for peptide transport activity of TAP has been developed. The radioactive label in the traditional assays has been replaced by a fluorescent label without compromising the transport efficiency of labeled peptide or the sensitivity of the assay. The use of multiscreen filtration plates has facilitated higher throughput and eliminated the centrifugation steps used in traditional TAP assays. The HTS assay shows similar kinetic characteristics as compared to the traditional assay. The HTS assay has been adapted on a Quadratrade mark 96-320 96-channel pipetting station (Tomtec, Hamden, CT) by optimizing time course, dose response of TAP to peptides and adenosine triphosphate (ATP), signal/noise ratio, reproducibility, and reagent stability. This HTS system has been utilized to screen a multiplexed compound library with a maximum of throughput 17,600 compounds per week. 相似文献
1000.
我们从腹泻病人便样中纯化了病毒,其结构蛋白组分按分子量大小分别为VP1(136K),VP2(113K),VP3(92K),VP4(84K),VP5(64K),VP6(47K),VP7(41K)。所有这些蛋白皆具有抗原性。WP6是B组轮状病毒的共同抗原。B组轮状病毒的每一结构蛋白与A组轮状病毒都无交叉免疫反应。另外注意到二例不同病人对VP6和VP7刺激产生的抗体水平不同。 相似文献