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Nonexchangeable proton resonances in the 500-MHz NMR spectrum of d-CTCGAGCTCGAG have been assigned by using two-dimensional correlated spectroscopy (COSY) and nuclear Overhauser enhancement spectroscopy (NOESY). 1H-1H coupling constants (J) in the deoxyribose rings have been measured by analyzing intensity and multiplet patterns in the phase-sensitive omega 1-scaled COSY spectra. A modification of the J-resolved technique, called amplitude-modulated J-resolved spectroscopy, has been described and used to increase the accuracy of J measurements. Absorption mode omega 1-scaled NOESY spectra at mixing times in the range 50-200 ms have been analyzed to monitor spin diffusion. A 50-ms spectrum has been used to estimate several interproton distances. The coupling constant and distance data have been used to arrive at sequence-specific sugar geometries and glycosidic torsion angles. The backbone structure has been refined by model building using the FRODO program, employing the sugar geometries and glycosidic torsion angles discussed above. The molecule shows interesting sequence-dependent variations in the structure. The cleavage site of the restriction enzyme XhoI exhibits unique differences in the sugar geometry and backbone torsion angles. 相似文献
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A 32-year-old phenotypic female with a history of nine consecutive abortions each in the first trimester was referred for cytogenetic studies. She was found to have 45,XX,t(22;22) (p11.1;q11.1) chromosomal pattern. The Ag-NOR banding technique showed that the NORs of both the acrocentrics involved in the translocation were deleted and the loss suffered from the elimination was compensated by the increased NOR activity as well as presence of dNOR on other acrocentric chromosomes. 相似文献
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Complete amino acid sequence of human seminal plasma beta-inhibin. Prediction of post Gln-Arg cleavage as a maturation site 总被引:8,自引:0,他引:8
The complete sequence of a 94 amino acid human seminal plasma polypeptide exhibiting inhibin-like activity is presented. This molecule, called beta-inhibin, selectively and specifically suppresses the release of pituitary FSH in vivo as well as in vitro. It does not affect the secretion of LH. Such a novel acidic protein contains a very basic C-terminal segment which is easily cleaved by mild tryptic digestion. It is predicted that the FSH inhibiting activity may reside within this region of the molecule. This would imply a post Gln-Arg cleavage to release the basic C-terminal active moiety. 相似文献
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Testosterone priopionate (TP) or estradiol-17 beta (E2) were injected into male and female rats from day of birth to 15 days of age to determine the effect of these steroids on the pituitary prolactin (PRL) level in developing rats. Animals were autopsied on Days 5, 7, 10, 14, 17, 22, 25, 30, 37, 45, 52, and 60 and pituitary PRL estimated by radioimmunoassay. Neonatal administration of TP or E2 markedly increased PRL content in male rats. The peak of PRL was advanced to Days 14 and 23, respectively, in E2- and TP-treated groups. The content of pituitary PRL declined sharply and values increased again by Day 52 in TP-treated rats and Day 37 in E2-treated rats. In the female rat both the steroids advanced the time of PRL peak. Peaks were observed on Days 22 and 30, respectively. Although PRL content declined following these peaks, values remained at a significantly higher level than normal. These results suggest that mechanisms controlling the PRL secretion are functional during the neonatal period. It is also suggested that TP acts to increase PRL levels by 1st being converted to E2. 相似文献
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Studies were carried out to investigate the influence of adrenalectomy on the 24 hour periodicity in the hypothalamo-pituitary axis in adult male rat. Adrenal gland ablation resulted in the shift in the occurrence of peak content of hypothalamic LHRH and attenuation in the responsiveness of the pituitary to synthetic LHRH. Following adrenalectomy, the circadian serum LH peak was attenuated and serum FSH showed a 24 hour periodicity. In conclusion, the results suggest the possible role of adrenal gland in the maintenance of 24 hour periodicity of hormones in the hypothalamo-hypophyseal axis in male rat. 相似文献