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1.
A study was made of the cellular origin of human immunoglobulins (γ2, γ1M, γ1A). The results indicated that two closely related families of cells form immunoglobulins in human lymphoid tissue: germinal (reticular) centers and plasma cells. Thus their cellular origin in addition to their known antigenic relations further justifies placing the immunoglobulins in one family of proteins. Immunoglobulins were also formed to a small extent in primitive reticular cells which resembled those of germinal centers but were separated from them. Possibly such cells were undergoing transition to the much more numerous plasma cells with which they were commonly associated. The mantles of small lymphocytes which surrounded germinal centers did not contain detectable quantities of immunoglobulins. While in general only one type of immunoglobulin was present in an individual cell or germinal center, γ2- and γ1M-globulin were identified on occasion in the same plasma cell and germinal center. A peculiarity of the fetal thymus gland was the presence of immunoglobulin, mainly γ1M, in a small number of cells of small and intermediate size and primitive reticular appearance and in Hassall's corpuscles. 相似文献
2.
Development of γG, γA, γM, β1C/β1A, C′1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, plasminogen, α1-antitrypsin, orosomucoid, β-lipoprotein, α2-macroglobulin, and prealbumin in the human conceptus
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The synthesis of γG, γA, γM, β1C/β1A, C′1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, α1-antitrypsin, orosomucoid, β-lipoprotein, α2-macroglobulin, and prealbumin was studied in 15 normal human embryos and fetuses of 29 days to 18 wk gestation and in the yolk sacs of four embryos from 5.5 to 11.5 wk gestation using tissue culture in 14C-labeled amino acids followed by radioimmunoelectrophoresis. The human embryo as early as 29 day gestation synthesized β1C/β1A, C′1 esterase inhibitor, transferrin, hemopexin, α1-antitrypsin, β-lipoprotein, α2-macroglobulin, and prealbumin in culture. At 32 days gestation ceruloplasmin and orosomucoid were also synthesized, but synthesis of fibrinogen was not observed before 5.5 wk. Synthesis of γM occurred as early as 10.5 wk gestation, and γG synthesis was found in cultures as early as 12 wk gestation; γA synthesis was not detected in any of the tissue cultures. With the exception of the γ-globulins, each of the proteins studied was synthesized by the liver, but additional sites of synthesis for some of these proteins were also found. Synthesis of γG and γM occurred primarily in the spleen, but other sites of synthesis were noted as well. 相似文献
3.
Oxygen Equilibrium Characteristics of Abnormal Hemoglobins: Hirose (α2β237Ser), L Ferrara (α247Glyβ2), Broussais (α290Asnβ2), and Dhofar (α2β258Arg)
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Shigeru Fujita 《The Journal of clinical investigation》1972,51(10):2520-2529
The oxygen equilibrium characteristics of four structural variants of hemoglobin A were correlated with their amino acid substitutions.Hemoglobin Dhofar, in which the proline at E2(58)beta is replaced by arginine, had normal oxygen equilibrium characteristics.Hemoglobin L Ferrara. in which the aspartic acid at CD5(47)alpha is replaced by glycine, and hemoglobin Broussais, in which the lysine at FG2(90)alpha is replaced by asparagine, both showed a slightly elevated oxygen affinity; nevertheless both demonstrated a normal heme-heme interaction and a normal Bohr effect.Hemoglobin Hirose, in which the tryptophan at C3 (37)beta is replaced by serine, showed abnormalities of all oxygen equilibrium characteristics; i.e., increased oxygen affinity, diminished heme-heme interaction, and reduced Bohr effect.These results suggest that aspartic acid at CD5(47)alpha and lysine at FG2(90)alpha are involved in the function of the hemoglobin molecule, despite the fact that these positions are not located directly in the heme or the alpha-beta-contact regions.Tryptophan at C3(37)beta is located at contact between alpha(1)- and beta(2)-subunits. It is suggested that the substitution by serine might disturb the quarternary structure of the mutant hemoglobin molecule during transition from oxy-form to deoxy-form resulting in an alteration of the heme function. 相似文献
4.
Ru Zhao Bing-Lin Zeng Wen-Qiang Jia Hong-Yi Zhao Long-Ying Shen Xiao-Jian Wang Xian-Dao Pan 《RSC advances》2020,10(57):34938
An efficient and mild method has been developed for the amination of β-methoxy amides (γ-lactones) including natural products michelolide, costunolide and parthenolide derivatives by using lithium chloride in good yields. This reaction is applicable to a wide range of substrates with good functional group tolerance. Mechanism studies show that the reactions undergo a LiCl promoted MeOH elimination from the substrates to form the corresponding α,β-unsaturated intermediates followed by the Michael addition of amines.The amination of β-methoxy amides (γ-lactones) including natural products michelolide, costunolide and parthenolide derivatives were first developed by using lithium chloride.The formation of carbon–nitrogen bonds remains one of the most fundamental and widely practiced reactions in organic synthesis, due to the prevalence of this functionality in the preparations of functional molecules in pharmaceutical chemistry, biochemistry and material sciences.1 Various synthetic methodologies have been developed to form C(sp2)-N bonds, including the Goldberg reaction,2 Buchwald–Hartwig reaction,3 imine reduction4 and the nucleophilic addition of carbon-nucleophiles to imine derivatives.5 Meanwhile, the formations of C(sp3)-N bonds can be achieved by reductive amination, which involves the conversion of a carbonyl group to an amine via an imine intermediate, such as Eschweiler–Clarke reaction6 and Borch reductive amination.7 Nucleophilic substitution of alkyl(pseudo)halides with amines (amine alkylation) serves as one direct strategy for the preparation of alkylamines, while the necessity of pre-installation of the halogen atoms and the production of stoichiometric inorganic salt wastes are considered as two main drawbacks for its application in large scale industrial synthesis.8Methoxy as the leaving group in the amination reactions has recently attracted the attention of organic chemists. For instance, Chiba and coworkers reported a method for the nucleophilic amination of methoxy arenes,9 which was achieved by using sodium hydride (NaH) in the presence of lithium iodide (LiI) through a concerted nucleophilic aromatic substitution pathway (Fig. 1a).10 Kondo and coworkers demonstrated that the organic superbase t-Bu-P4 efficiently catalyzes the amination of methoxy(hetero)arenes with the amine nucleophiles (Fig. 1b).11 The t-Bu-P4 is also suitable to catalyze the amination of β-(hetero)arylethyl ethers with amines to synthesize β-(hetero)arylethylamines (Fig. 1c).12 Sun and coworkers reported that C–S bond cleavage to access N-substituted acrylamide and β-aminopropanamide(Fig. 1d).13Open in a separate windowFig. 1Amination reactions of methyl ethers.Recently, we described the application of a CuBr–LiCl composite for the short-chain alkoxylation of aryl bromides.14 During that course of study, the single-shell lithium ion was found to embrace a unique affinity for oxygen and can be used as an additive to activate C–O bond and facilitate the nucleophilic reaction. On the basis of this study, we herein present the synthesis of β-amino amides (γ-lactones) via the elimination of methoxy group followed by Michael addition of an amine, that was promoted by LiCl in good yields under conventional conditions.We initiated our study with the reaction of 3-methoxy-N-phenylpropanamide 1a and piperidine 2a in the presence of lithium salts ( Entry Additive (equiv.) Solvent T (°C) Time (h) Yieldb (%) 1 LiCl (2.0) iPrOH 120 12 70 2 LiBr (2.0) iPrOH 120 12 30 3 LiI (2.0) iPrOH 120 12 43 4 LiOTf (2.0) iPrOH 120 12 38 5 Li2CO3 (2.0) iPrOH 120 12 6 6 NaCl (2.0) iPrOH 120 12 N. R. 7 LiCl (2.0) DMF 120 12 46 8 LiCl (2.0) Toluene 120 12 21 9 LiCl (1.0) iPrOH 120 12 38 10c — iPrOH 120 12 N. R. 11 LiCl (2.0) iPrOH 80 12 23 12 LiCl (2.0) iPrOH 120 6 49