排序方式: 共有4条查询结果,搜索用时 15 毫秒
1
1.
2.
The solubility of crystalline deoxygenated sickle-cell hemoglobin has been determined by a new turbidometric technique. In the absence of the allosteric effector, inositol hexaphosphate, the solubility of sickle deoxyhemoglobin crystals is about 30% less than that of gels. The dependence of the solubility of crystals on temperature at pH 7.1 is very much the same as that of gels at pH 6.48. The change in Van't Hoff enthalpy with crystallization is positive but small (3.11 kcal mol?1) and essentially independent of temperature below 30 °C. The presence of inositol hexaphosphate cuts the solubility almost in half. The entropy change when crystals form, just under 40 cal K?1 mol?1, is larger than the values of ΔS ° found for gels. None of the measurements reported required the estimation of pellet volumes and compositions. 相似文献
3.
Suppression of the fourth component of complement in vitro was examined by exposing cultured guinea pig peritoneal cells to anti-C4 alloantisera or to control sera. We found that in contrast to similar experiments in vivo, C4 production could be suppressed by specific anti-C4 antisera over a wide range of doses with complete regularity. The suppression was not permanent, however, and postsuppression stimulation of C4 was frequently seen after recovery from suppression. Production of C2 and β-glucuronidase were also measured in these experiments. C2 was not suppressed by the anti-C4 treatment but stimulation of C2 was seen in those instances where C4 production was stimulated. β-Glucuronidase was neither suppressed nor stimulated. Purified IgG1 IgG2 and (Fab′)2 fragments were as effective in causing suppression and postsuppression stimulation as whole antibody preparations. This suggests that complement activation, Fc receptors, and complement receptors do not play a significant role in these in vitro phenomena. 相似文献
4.
Isolation and characterization of faithful and altered clones of the genomes of cauliflower mosaic virus isolates Cabb B-JI, CM4-184, and Bari I 总被引:3,自引:0,他引:3
Full-length genomes of cauliflower mosaic virus (CaMV) isolates Cabb B-JI, CM4-184, and Bari I have been cloned in the SalGI site of plasmid pAT 153. The cloned DNAs were characterized by restriction mapping and infectivity assays. All the sites present in the virion DNAs were found in the cloned DNAs. Comparison of restriction maps with those of DNA from two other isolates which have been recently completely sequenced revealed a close relationship among the different isolates. Some of the clones appear to be faithful copies of the viral genomes and these viral inserts are infectious when inoculated into turnip plants. Various clones with deletions in the CaMV DNA have been isolated and characterized. Some of them may correspond to deletions naturally occurring in a subpopulation of the virus whereas others occurred during cloning. None of the deleted fragments are infectious when inoculated into plants. Strikingly, all the deletions overlap one or two of the specific single-stranded breaks characteristic of caulimoviruses, suggesting that sequences surrounding the breaks are not dispensable. 相似文献
1