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1.
2.
The sensitivity of the fluorescent dye, 3,3′-diethylthiadicarbocyanine (DiS-C2(5)), was too low for the detection of membrane potential changes in rat small intestinal membrane vesicles. Only after adding LaCl3 or after fractionation of the intestinal membranes by free-flow electrophoresis could the dye be used to monitor electrogenic Na+-dependent transport systems. It is concluded that the response of this potential-sensitive dye is influenced by the negative surface charge density of the vesicles. 相似文献
3.
《Bioscience, biotechnology, and biochemistry》2013,77(7):1181-1182
The epitopes of the major soybean allergen, Gly m Bd 30K, recognized by mouse monoclonal antibodies H6 and F5 were investigated by using synthetic peptides bound to pins. The epitopes are shown to be localized in peptide 31QGGCGRGWAFSATGAI-EA48 for H6, and in 115 DKVTIDGYETLIMSDEST132 for F5. 相似文献
4.
C. Steven McDaniel Taghi Manshouri M. Zouhair Atassi 《Journal of Protein Chemistry》1987,6(5):455-461
A peptide corresponding to residues 26–41 of α-bungarotoxin, and closed by a disulfide bond between two cysteine residues
at the amino and C terminal ends of the peptide, was synthesized and the monomeric form was purified. The peptide, which represents
the exposed part of the long central loop of the toxin molecule, was examined for binding to acetylcholine receptor. The peptide
was shown by radiometric titrations to bind radiolabeled receptor, and radiolabeled peptide was bound by receptor. The specificity
of the binding was confirmed by inhibition with the parent toxin. A synthetic analog of the peptide in which Trp-28 was replaced
by glycine had very little (10%) of the original activity. Succinylation of the amino groups of the peptide resulted in virtually
complete (98%) loss of the binding activity. These results indicate that a shortened loop peptide corresponding to the region
26–41 of α-bungarotoxin exhibits binding activities mimicking those of the parent molecule. In this region, Trp-28, and one
or both of Lys-26 and Lys-38, are essential contact residues in the binding to receptor. 相似文献
5.
Synthetic peptide SH624 (SHHPARTAHYGSLPQK), residues 59–74 of human myelin basic protein (MBP) was found to be encephalitogenic in the rabbit. Four antisera raised, against the peptide were employed in a liquid-phase equilibrium competitive radioimmunoassay with a series of synthetic peptide analogs of the region to probe the structural requirements of the B-cell determinant subsumed within SH624. The cross-reactivities of the four antisera with intact MBP were also examined. Immunochemical analyses of the four antisera suggested specificities directed against a conformational determinant dependent upon residues from the more phylogenetically conserved carboxyl C-terminal region, residues 65–74 (TAHYGSLPQK) of the synthetic immunogen. Peptide analogs shorter than SH624 from the C-terminal end showed no cross-reactivity with any of the reagent antisera while analogs shorter from the N-terminal end and including the encephalitogenic sequence TTHYGSLPQK, as well as, HYGSLPQK were reactive under equilibrium competitive conditions. SH624-reactive antibodies, cross-reactive with purified heterologous MBPs from 10 different species were also identified in all four reagent antisera. The results of these experiments support previous investigations demonstrating the accessibility of the encephalitogenic 65–74 region in intact MBP. They also underscore the importance of B-cell recognition of organ specific antigenic determinants with respect to MBP immunology and, in particular, the recognition of autoreactive determinants in the neighborhood of encephalitogenic centers. 相似文献
6.
Asim Esen 《Journal of Protein Chemistry》1990,9(4):453-460
The immunochemical data from studies with polyclonal antisera to -zein1, the 27 kD component of the maize prolamin, indicated that the region containing 8 tandem repeats of the sequence PPPVHL is an immunodominant site. In one case, the entire antibody repertoire of an antiserum recognized epitope(s) within this region. Three 17-mer oligopeptides corresponding to the predicted antigenic epitopes of -zein1 were synthesized and reacted with three different anti--zein1 sera in order to map antigenic sites in the intact protein. These antisera yielded positive reactions with a 17-mer peptide (peptide 37), which was not in a hydrophilic maximum but derived from the repeat region. The same antisera gave little or no reaction with other peptides (peptides 38 and 39), both of which were in a hydrophilic maximum. In addition, an antiserum to peptide 37 reacted strongly with both the homologous antigen and the intact -zein1. Peptide 37 also blocked the binding of antisera to -zein1 in competition assays. Subsequently, the shorter 6-mer (peptide 82) and 12-mer (peptide 80) versions of peptide 37 were synthesized, and both reacted with anti-peptide 37 serum and also with each of the three anti--zein1 sera. In these reactions and in competition assays, the reactivity and the blocking ability increased in proportion to the length of the peptide. Based on these data, it was concluded that the repeat region of -zein1 is the site of one or more continuous immunodominant epitopes. The data also suggest that the repeat region is exposed on the surface of the folded protein and probably occur as a mobile, random coil. 相似文献
7.
A general method is described for the assay of glycosyltransferase activity, which makes use of synthetic glycoside acceptors attached to hydrophobic aglycones. The products formed by incubation of an enzyme with acceptor and radiolabelled sugarnucleotide can then be rapidly (one minute) separated from interfering radioactivity by adsorption on to reverse-phase C-18 cartridges. After aqueous washing, products are easily isolated by elution with methanol. The utility of the method for the assay of (1–4)galactosyltransferase, (1–2)fucosyltransferase andN-acetylglucosaminyltransferase I and V is demonstrated. 相似文献
8.
Biserka Mulac-Jericevic Taghi Manshouri Tsuyoshi Yokoi M. Zouhair Atassi 《Journal of Protein Chemistry》1988,7(2):173-177
A set of 18 synthetic uniform overlapping peptides spanning the entire extracellular part (residues 1–210) of the -subunit of human acetylcholine receptor were studied for their binding activity of125I-labeled -bungarotoxin and cobratoxin. A major toxin-binding region was found to reside within peptide 122–138. In addition, low-binding activities were obtained with peptides 34–49 and 194–210. It is concluded that the region within residues 122–138 constitutes a universal major toxin-binding region for acetylcholine receptor of various species. 相似文献
9.
Abstract. To study whether an electrical potential difference exists across the nuclear envelope or inner nuclear membrane of plant cells, the authors have used an optical probe of membrane potential, the cationic fluorescent dye, DiOC6 (3) (MW = 572.5). This dye was microinjected into the nucleoplasm of isolated Acetabularia nuclei (which are still surrounded by a thin layer of cytoplasm) and its subnuclear localization visualized by fluorescence microscopy. Striking differences, which seemed to be correlated with the developmental stage of the isolated nucleus, were observed. In nuclei isolated from cells at the stage of early cap stage formation, the dye was restricted to the nuclear envelope. In nuclei isolated from cells with intermediate or fully developed caps, there was increased nucleoplasmic staining, and the staining of the envelope was frequently diminished or abolished. In all nuclei, the dye remained within the nucleus after injection. Cytoplasmic staining was only observed when nuclei isolated from cells at the stage of early cap formation were incubated in a hyper- or hypo-tonic medium. Various ionophores, injected before the dye into the nucleoplasm, had no effect on the subsequent nuclear localization of DiOC6 (3), although they did rapidly induce nucleolar condensation in nuclei isolated from cells at the stage of early cap formation. The results suggested that the electrical properties of Acetabularia nuclear envelopes or inner nuclear membranes change during cell maturation. Furthermore, the retention of the dye in the nucleoplasm under isotonic conditions indicated that the nuclear pores were not open channels for molecules of this size. 相似文献
10.
Magdalena T. Tosteson Michael P. Caulfield Jay J. Levy Michael Rosenblatt Daniel C. Tosteson 《Bioscience reports》1988,8(2):173-183
We have used the chemically synthesized sequence of pre-pro-parathyroid hormone and several of its analogues to test the notion that the capacity of amphipathic peptides to aggregate in membranes and form ion-permeable channels correlates with their ability to function as signal sequences for secreted proteins. We found that pre-pro-parathyroid hormone (the signal sequence and pro-region of parathyroid hormone (M)), as well as some of its analogues, forms aggregates of monomers which are ion-permeable. The ion-permeable aggregates (2–3 monomers) formed by (M) are voltage-dependent and are more permeable for cations than for anions. The compounds which formed ion channels in bilayers also acted as potential signal sequences. We conclude that the ability of peptides to form ion-permeable pathways in bilayers may be correlated to their ability to function as signal peptides. 相似文献