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1.
2.
Novel approach to the study of the antigenicities and receptor functions of carbohydrate chains of glycoproteins 总被引:4,自引:0,他引:4
P W Tang H C Gool M Hardy Y C Lee T Feizi 《Biochemical and biophysical research communications》1985,132(2):474-480
This report describes the construction of neoglycolipids as a novel approach to determining the antigenicities and receptor functions of minute amounts of oligosaccharides derived from glycoproteins. Reduced oligosaccharides are converted into oligosaccharide alditols by controlled selective periodate oxidation and conjugated to phosphatidyl ethanolamine dipalmitoyl by reductive amination. The resulting neoglycolipids can be rendered multivalent by binding to polyvinylchloride or silica plates or they can be incorporated into liposomes and their antigenicities and receptor activities determined in low concentrations by direct binding or inhibition of binding assays. This approach, which has been successfully used with two monoclonal antibodies and a plant lectin, should be widely applicable to the direct analysis of O- and N-glycosidically linked carbohydrate chains of glycoproteins and proteoglycans both as antigens and recognition structures of diverse receptor systems. 相似文献
3.
S R Carding S J Thorpe R Thorpe T Feizi 《Biochemical and biophysical research communications》1985,127(2):680-686
Immunofluorescence and immunoblotting experiments, using a monoclonal antibody to the 13 kDa mammalian beta-galactoside-binding lectin have shown that human lymphocytes contain nuclear and cytoplasmic proteins of apparent molecular masses of 130, 80, 65 and 13 kDa that are antigenically related to the lectin and whose levels and patterns of expression change in association with transformation, or after stimulation with mitogens. These observations, together with the finding that the myeloid cell line K562 is also rich in the 130 kDa component, whereas the mature granulocytes of normal donors and of patients with chronic myeloid leukaemia are lacking in all of the immunoreactive forms, raise the possibility that this family of lectin-related proteins may be components of growth regulatory systems that are variously elicited in the transformed and stimulated cells. 相似文献
4.
小鼠脾细胞经重组人白细胞介素-2(rhIL-2)激活后对YAC-1,LP-3和WEHI-164等肿瘤细胞均有很强的杀伤活性。在CFU-E和BFU-E培养体系中,不同浓度LAK细胞与BMC直接加入或预温育4h后再培养,均能加强CFU-E和BFU-E增殖。低浓度LAK细胞(LAK/BMC为0.5)与BMC直接加入或预温育后再加入CFU-mix培养体系中,均能增强CFU-mix增殖,而高浓度LAK细胞和BMC(LAK/BMC=8.0)直接加入培养体系则抑制CFU-mix增殖;若共温育后再培养则非常明显地抑制CFU-mix增殖,CFU-mix仅为对照的17.6%。小鼠LAK细胞对造血祖细胞体外增殖具有调节作用,这种调节可能包括分泌某些细胞因子以及细胞间直接相互作用两种方式。 相似文献
5.
Nielsen J; Peixoto AA; Piccin A; Costa R; Kyriacou CP; Chalmers D 《Molecular biology and evolution》1994,11(6):839-853
The region of the clock gene period (per) that encodes a repetitive tract
of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran
species both within and outside the Drosophilidae. All the non-
Drosophilidae sequences in this region are short and present a remarkably
stable picture compared to the Drosophilidae, in which the region is much
larger and extremely variable, both in size and composition. The
accelerated evolution in the repetitive region of the Drosophilidae appears
to be mainly due to an expansion of two ancestral repeats, one encoding a
Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and
asparagine or threonine. In some drosophilids the expansion involves a
duplication of the pentapeptide sequence, but in Drosophila pseudoobscura
both the dipeptide and the pentapeptide repeats are present in larger
numbers. In the nondrosophilids, however, the pentapeptide sequence is
represented by one copy and the dipeptide by two copies. These observations
fulfill some of the predictions of recent theoretical models that have
simulated the evolution of repetitive sequences.
相似文献
6.
The neoglycolipid technology comprises several microproceduresinvolving the generation of lipid-linked oligosaccharide probesfor carbohydrate recognition studies in conjunction with oligosaccharidesequence determination by mass spectrometry. Although applicableto any desired oilgosaccharides, procedures are greatly facilitatedif the ohgosaccharides are nonreduced, as conjugation is byreductive amination of a reducing end aldehyde to a phosphatidylethanolamine.Using bovine submaxillary mucin as a model for release of O-glycansin the reducing state, and based on yields of neoglycolipidsand side-products from "peeling" reactions and degradation,aqueous ethylamine 70% w/v at 22°C for 48 h has been selectedin preference to other conditions, triethylainine, sodium hydroxide,and bydrazine. The integrity of the main acidic and neutraloligosaccharides released under these conditions, di- to octasaccharides,was established by analyses of free oligosaccharides by liquidsecondary ion mass spectrometry (LSIMS) and of the derived neoglycolipidsby TLCLSIMS; the repertoire compared favorably with that ofthe oligosaccharide alditols generated by conventional reductivealkaline borohydride treatment. More forcing conditions of ethylamine70% w/v at 65°C for 6 h were required to release oligosaccharidesfrom porcine gastric mucin; di- to nonasaccharides were obtainedof which about one-third had an intact core GalNAc. Relativeto yields after reductive alkaline hydrolysis, the overall yieldsfor these two glycoproteins were 20% and 4050% for acidicand neutral oligosaccharides, respectively. Among O-glycansreleased from an ovarian cystadenoma glycoprotein using ethylamine,three variants of the sulfated Lea/x sequences were identifiedas ligands for the endothelial adhesion molecule E-selectin,one of which is based on the unusual backbone Gal-3/4GlcNAc-3Gal-3Gal. mucins O-linked oligosaccharides TLC-LSIMS neoglycolipids E-selectin 相似文献
7.
Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene 总被引:8,自引:1,他引:7
We have analyzed the conserved regions of the gene coding for the
circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria
parasite. The closest evolutionary relative of P. falciparum, the agent of
malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is
consistent with the hypothesis that P. falciparum is an ancient human
parasite, associated with humans since the divergence of the hominids from
their closest hominoid relatives. Three other human Plasmodium species are
each genetically indistinguishable from species parasitic to nonhuman
primates; that is, for the DNA sequences included in our analysis, the
differences between species are not greater than the differences between
strains of the human species. The human P. malariae is indistinguishable
from P. brasilianum, and P. vivax is indistinguishable from P. simium; P.
brasilianum and P. simium are parasitic to New World monkeys. The human P.
vivax-like is indistinguishable from P. simiovale, a parasite of Old World
macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are
evolutionarily recent human parasites, the first two at least acquired only
within the last several thousand years, and perhaps within the last few
hundred years, after the expansion of human populations in South America
following the European colonizations. We estimate the rate of evolution of
the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year.
The divergence between the P. falciparum and P. reichenowi lineages is
accordingly dated 8.9 Myr ago. The divergence between the three lineages
leading to the human parasites is very ancient, about 100 Myr old between
P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between
P. falciparum and the other two.
相似文献
8.
Photosynthetic enhancement studies performed at 619 nm (excitation of Systems I and II) and at 446 nm (mainly excitation of System I) revealed an 18% photosynthetic enhancement simultaneously with a 31% reduction in glycolate excretion. This observation supports the hypothesis that some glycolate may be consumed in an oxidation process associated with System I when System II is poorly excited and the supply of electrons from the water splitting process of photosynthesis is low. 相似文献
9.
The thin-layer-chromatography immunostaining procedure was applied to human erythrocyte glycolipids using monoclonal anti-i and anti-I antibodies which are directed against epitopes on linear and branched carbohydrate chains of the neolacto (poly-N-acetyl-lactosamine) series. An examination of native and mild-acid-treated glycolipids from normal adult (Iadul t antigen type), neonatal (icord) , and I-antigen-deficient adult (iadult) erythrocytes enabled certain structural inferences to be made as follows: (a) cells of both I and i phenotypes contain a multiplicity of glycolipids of the neolacto series whose backbones consist of 8 or more sugar residues; (b) the octasaccharide backbones are predominantly linear in cells of i phenotype and branched in those of I type; and (c) more complex glycolipids having decasaccharide and larger backbones with both linear and branched sequences occur in erythrocytes of both phenotypes, 0 相似文献
10.
H. C. Gool J. Schlessinger I. Lax Y. Yarden T. A. Libermann T. Feizi 《Bioscience reports》1983,3(11):1045-1052
The hybridoma antibody TL5, which precipitates the EGF receptor from the human epidermoid carcinoma cell line A431, has been shown to recognize the blood-group-A carbohydrate structure. This conclusion has been reached from studies of (a) the binding of the antibody to glycoproteins and haemagglutination of erythrocytes with known blood-group-antigen activities and (b) the inhibition of binding of the antibody to a radiolabelled blood-group-A-active glycoprotein by structurally defined oligosaccharides. 相似文献