摘要:

AbstractThe amino acid compositions of homologous tryptic peptides, as well as the amino acid sequences of complete peptide chains, are compared in hemoglobins of different species. Special attention is given to the analyses of mammalian and fish hemoglobins. The multiplicity of hemoglobins in one species and the differences between the hemoglobins of different species are considered. These differences are discussed in view of base exchanges, deletions, insertions, and gene duplications.Enormous differences are found between any two single hemoglobin chains. The number of amino acids varies from 127 to 156 residues. In comparing all the hemoglobins, only eight amino acids are found in identical positions (invariant residues). All hemoglobins analyzed to date follow the rule of “isopolar substitution” of Perutz, Kendrew, and Watson. The results are summarized and considered with regard to certain parallels in the morphol

ISSN:0021-9541    

DOI:10.1002/jcp.1040670404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractPrecision scale models of sickle cell hemoglobin molecules indicate that the genetic substitution of valine for glutamic acid at the sixth position in the two β chains allows an intramolecular hydrophobic bond to form. This changes the conformation in such a way as to allow molecular stacking. Results of subjection of Hb S solution to temperature change and to propane are consistent with the presence of such a bond. Examination of sickled erythrocytes in a magnetic field and in polarized light indicates that the Hb S molecules are alignedin situ. Filaments interpreted as hollow cables of six Hb S monofilaments have been demonstrated by electron microscopy

ISSN:0021-9541    

DOI:10.1002/jcp.1040670405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractPrevious evidence that the specificity of antibodies is determined by differences in their primary structure was based on the finding of characteristic differences in the average amino acid compositions of five purified rabbit antibodies. These differences were shown to be independent of those associated with the allotypic specificities of rabbit γ G‐immunoglobulins and independent of the charge on the determinant group of the antigens employed. Further support was provided by recent studies of the location of the amino acid differences in the antibody structures. (1) The differences were found to be distributed in both the light and heavy polypeptide chains, which correlated with immunological data indicating that both chains contribute to the formation of the active site. (2) The amino acid differences were all located in an active fragment obtained after cleavage of the C‐terminal half of the heavy chain with cyanogen bromide. Further fractionation of this active fragment showed that the amino acid differences observed in the heavy chains were localized in the N‐terminal half known to be involved in the active site. The simplest interpretation of these results is that antibody formation is a genetically controlled process. However, the finding that the light chain from any one antibody was heterogeneous with respect to its amino acid content despite its average characteristic composition raises the possibility that mechanism of antibody synthesis may not be analogous to that of other proteins. Proposed normal and abnormal mechanisms are discussed in relation to both these data on antibody primary structure and the data on the primary structure of the related myeloma pr

ISSN:0021-9541    

DOI:10.1002/jcp.1040670406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractSubunits of immunoglobulins have been prepared by two methods, both of which have contributed to our knowledge of the structural basis of antibody specificity. The first method is enzymic hydrolysis with either papain or pepsin and leads to the unequivocal conclusion that each combining site is contained in a fragment (Fab) of about 45,000 molecular weight and formed from the light chain and the N‐terminal half of the heavy chain, the Fd fragment. The second method of preparing subunits is to reduce the interchain disulfide bonds and to isolate the chains. This should decide whether the combining site is in the Fd fragment, the light chain, or is formed jointly by both. In fact, considerable loss of affinity for the antigen follows, whatever technique is used to dissociate the peptide chains and, although many papers have been published on this subject, no definite answer has yet been obtained. Although the majority opinion probably favors the view that both chains are concerned in the formation of the combining site, our tentative conclusion is that the site is placed entirely in the heavy chain and that the light chain has only a semispecific role in facilitating the reformation of the native configuration of the heavy chain after its disruption under the conditions necessary for dissociation of the two chain

ISSN:0021-9541    

DOI:10.1002/jcp.1040670407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe structural genes for the chains of hemoglobin control not only the amino acid sequence but also the net rate of synthesis of the chains. In some cases, high rate of destruction associated with a structural abnormality is an important factor in net synthesis. Balanced net production of α and β chains is probably maintained by selection against mutations that result in gross imbalance, since gross imbalance causes hemolytic anemia or death. Minor imbalances may be compensated for by destruction of excess chains without destruction of red blood cells. A proposed model for control of rate of synthesis of the globin chains postulates that completed chains are released from mRNA at a rate determined by the slowest step in their assembly. Decreased synthesis can result from a mutation that results in a slower step anywhere along the mRNA. On the other hand, increased synthesis can only result from a change in the specific position of the rate‐limiting s

ISSN:0021-9541    

DOI:10.1002/jcp.1040670408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe genetics of immunoglobulins (Ig) has been discussed from the standpoint of the determinism of the antigenic specificities of different kinds that they carry: isotypic specificities, which are uniform in all individuals of the same animal species; allotypic specificities, which are not the same in all individuals, but are uniform within groups of individuals; idiotypic specificities, each of which not only is particular to the antibody against one given antigen but is, in addition, variable with individuals.Allotypic variants of the Ig are mainly these: in the rabbit, of the L polypeptide chains (abgroup) and of the IgG chains (aagroup); in man, of the L chains (Inv system) and of the IgG H chains (Gm system); in the mouse, of the IgG and IgA H chains. The control of the allotypic variants of the IgG H chains is mediated in man and mouse by alleles at several closely linked loci which were distinguished, with the help of myeloma proteins, because of differences in isotypic specificities. In the mouse, these loci are closely linked also to the locus which controls the IgA H chains. Several linked loci are also responsible for the IgG H chains of rabbits, and nearly certainly for their L chains.The cellular aspect of the genetics of immunoglobulins has been reviewed with the main conclusion that each cell seems to be specialized in the synthesis of Ig made of H and L chains of only one allotypic kind. The number of cells specialized in the synthesis of one kind of molecules seems to be proportional to the concentration of these molecules in serum.

ISSN:0021-9541    

DOI:10.1002/jcp.1040670409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe mediastinal nodes of untreated rats contain medullary cords populated by variously matured plasmocytes, classified into large, medium, and small on the basis of nuclear diameters. Since hemocytopoietic cells proliferate while maturing and since proliferation yields progressively greater numbers of mitoses, it follows that the order of mitotic increment of the variously matured plasmocytes can tell the position of each type in the plasmocytic series. Counts were carried out in 32 rats killed at four successive 6‐hour intervals. For 3000 plasmocytes counted perrat, there was an average of 10, 26, and 34 mitoses of large, medium, and small plasmocytes respectively. On the basis of an equal mitotic duration for all plasmocytes, this indicated that the large plasmocytes yield the medium plasmocytes which, in turn, give rise to the small plasmocytes. The number of generations of each type of plasmocyte was determined by comparing the experimental ratios, for number of mitoses of a progeny type of plasmocyte over that of its progenitor type, with similar theoretical ratios expected for variable numbers of generations of progeny and progenitor cells. Comparisons indicated that there are likely four generations of large plasmocytes followed by two of medium plasmocytes and also two of small plasmocytes. As for the nature of the ultimate precursors of the large plasmocytes, it is postulated that they are the hypertrophied endothelial cells of the nodes' postcapillary venules. These cells would receive the appropriate stimulus for plasmocytic differentiation from the small lymphocytes which cross them to enter these venule

ISSN:0021-9541    

DOI:10.1002/jcp.1040670410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

ISSN:0021-9541    

DOI:10.1002/jcp.1040670411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractFour different assay methods of bone marrow stem cells have been examined with regard to the kinetic pattern following perturbation of the steady‐state system,e.g., by irradiation. Basically, the stem cell assays fall into two categories: those depending on grafting hemopoietic cells into suitably treated recipients, and those in which recovery of the population is allowed in the animal in which the perturbation was produced, without handling the cells. Evidence is accumulating which indicates that in the grafting techniques, a selective loss of stem cells may occur, especially stem cells in cell cycle; hence, in early stages of recovery of the population, unduly low numerical values might be noted. In view of this evidence, the concept of the colony‐formingcellmay have to be replaced by the concept of the colony‐formingpropertyof the stem

ISSN:0021-9541    

DOI:10.1002/jcp.1040670412

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe proper development of the organs of the immune system is dependent on at least three factors: (1) the development of anlagen with the capacity to trap antigens and support the proliferation of lymphoid and plasma cell precursors; (2) the production by the bone marrow of lymphoid and plasma cell precursors which seed in the lymphoid organs; and (3) the thymus, which seeds reactive cells to the lymphoid organs and produces a humoral factor stimulating antigen‐triggered proliferation of primitive lymphoid and plasma cells. Studies on cell population changes in the lymph nodes following thymectomy in mice confirm earlier evidence that most cells produced in the thymus do not seed to the lymphoid organs, but die locally in the thymu

ISSN:0021-9541    

DOI:10.1002/jcp.1040670413

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY