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1.
A comprehensive synthetic approach consisting of a series of consecutive, uniform overlapping peptides encompassing the entire protein chain was recently used to determine the full antigenic profile of the -chain of human hemoglobin (Hb). The peptides synthesized enabled the localization of five major continuous antigenic regions within the chain. The present findings describe the delineation of an antigenic site (site 2) residing within the region 41–65. Ten peptides representing the -chain regions 41–55, 51–65, 45–54, 45–56, 45–58, 45–60, 48–56, 49–56, 50–56, and 51–56 were synthesized and purified. Quantitative radioimmunoadsorbent titrations were used to determine binding to peptide adsorbents of radioiodinated anti-Hb antibodies that were raised in rabbit, goat, and outbred mouse. In one set of peptides, the N-terminal was fixed while the C-terminal end was increased by increments of two residues from Gln-54 to Lys-60 (i.e., peptides 45–54, 45–45, 45–58, and 45–60). Binding studies revealed that maximum antibody activity resided in peptide 45–45, indicating that Lys-56 marks the C-terminal boundary of the site. In the second set of peptides, the C-terminal was fixed at Lys-56 while the peptides were elongated at their N-terminal by one-residue increments from Gly-51 to Leu-48. Antibody-binding studies with these peptides indicated that Ser-49 defines the N-terminal boundary of the site. Therefore, the antigenic site within region 41–65 of the chain comprises residues 49–56. The relevance of these findings to the immune recognition of Hb and other proteins is discussed. 相似文献
2.
Doriana Fruci Paolo Rovero Richard H. Butler Rosa Sorrentino Roberto Tosi Nobuyuki Tanigaki 《Immunogenetics》1993,38(1):41-46
Eight nonamer peptides that comply with the major anchor residue motifs (the combination of amino acid residues at positions 2 and 9), R-K and R-R, of HLA-B27 (B*2705)-binding peptides were synthesized and tested for their direct binding to HLA class I alpha chains by the HLA class I alpha chain refolding assay previously described. One was a known B27 (B*2705)-binding heat shock protein peptide, HSP89 (201–209), and the other seven were derived from the sequence of wild-type P53, a human tumor suppressor protein. A total of 36 HLA class I allospecificities were tested. HSP89 (201–209) and two P53 peptides, P53 (362–370) and P53 (378–386), all possessing the motif R-K, bound strongly to B27 (B*2705) alpha chains. A weak binding was seen for P53 (272–280) and P53 (334–342), both showing the motif R-R. Most of these B27-binding peptides were found to bind to A3 alpha chains as well. In addition, P53 (173–181) and P53 (334–342), both with the R-R motif, showed substantial binding with A31 alpha chains. All the peptides, carrying the motif R-K also showed weak binding with A31 alpha chains. The remaining two peptides, P53 (201–209) and P53 (282–290), with the motif R-R, did not show significant bininding with any of the alpha chains tested. This study demonstrates both the specificity of peptide binding to a given HLA allelic product and the occurence of cross-peptide-binding between the allelic products of different HLA loci.
Correspondence to: N. Tanigaki. 相似文献
3.
Chromogranin A is an acidic protein that is costored and cosecreted with parathyroid hormone (PTH) from parathyroid cells. Pancreastatin (PST), is derived from chromogranin A, and inhibits secretion from several endocrine/neuroendocrine tissues. Effects of different pancreastatin peptides were investigated on dispersed cells from bovine and human parathyroid glands. Bovine PST(1–47) and bovine PST(32–47) inhibited PTH release from bovine cells in a dose-dependent manner. The former peptide was more potent and suppressed the secretion at 1–100 nM. This inhibition was evident in 0.5 and 1.25 mM, but not in 3.0 mM external Ca2+. Both peptides failed to alter the concentration of cytoplasmic Ca2+([Ca2+]i) of bovine cells. Human PST(1–52) and PST(34–52) did not affect PTH release or [Ca2+]i of parathyroid cells from patients with hyperparathyroidism, nor [Ca2+]i of normal human parathyroid cells. Furthermore, bovine PST(1–47) and bovine PST(32–47) failed to alter the secretion of abnormal human parathyroid cells. The study indicates that PST exerts secretory inhibition on bovine but not human parathyroid cells, and that this action does not involve alterations of [Ca2+]i. 相似文献
4.
A comparative study of various procedures for tryptophanyl peptide bond cleavage by BNPS-skatole [2-(2-nitrophenyl)-3-methyl-3-bromoindolenine] was carried out on native and on reduced and alkylated bovine -lactoglobulin (BLG). The reaction yield and the composition of the derived products were studied in acetic acid, trifluoroacetic acid (TFA), and ethanol/TFA. For BNPS-skatole removal, extraction by water or ethyl ether was compared with dialysis and gel filtration. The three expected peptides (1–19, 20–61, 62–162) and incomplete cleaved fragments (1–61, 20–162) were separated and characterized by electrophoresis, reverse-phase high-performance liquid chromatography, and mass spectrometry. The highest hydrolysis yield (67.4%) occurred with native BLG cleaved in 88% acetic acid at 47°C for 60 min. Subsequent water extraction and gel filtration led to total recovery of the material, but reagent elimination was only quantitative after gel filtration. Cleavage specificity was ensured by mass spectrometry and the amino acid composition of peptides 1–19 and 62–162. The chemical side reactions identified are discussed. 相似文献
5.
Lone Banke Rasmussen Birgit Hollenbach Peter Laurberg Allan Carl Antonia Hg Torben Jrgensen Pernille Vejbjerg Lars Ovesen Lutz Schomburg 《Journal of trace elements in medicine and biology》2009,23(4):265-271
Selenium is an essential micronutrient important to human health. The main objective of this study is to describe serum selenium and selenoprotein P status in two samples of the Danish population. In addition, the influence of various factors potentially associated with selenium status was investigated.Blood samples from a total of 817 randomly selected subjects from two cities in Denmark were analyzed. Half of the samples were collected in 1997–1998 and the other half in 2004–2005. Samples from women aged 18–22, 40–45 and 60–65 years, and men aged 60–65 years were selected for this study. All subjects had filled in a food frequency questionnaire (FFQ) and a questionnaire with information about smoking habits, alcohol consumption and exercise habits.Mean serum selenium level was 98.7±19.8 μg/L and median selenoprotein P level was 2.72 (2.18–3.49) mg/L. Serum selenium and selenoprotein P increased with age, and selenoprotein P was higher in men than in women. Serum selenium levels decreased by 5% on average from 1997–98 to 2004–05 (P<0.001), whereas selenoprotein P level increased (P<0.001). The intake of fish correlated weakly with serum selenium level (r=0.14, P<0.001) but not with selenoprotein P level. Smoking status, alcohol intake, exercise habits, BMI and medicine use did not influence selenium status.It is concluded that selenium status in this Danish population is at an acceptable level. No major groups with regard to age, sex or lifestyle factors could be identified as being in risk for selenium deficiency. 相似文献
6.
The purpose of the present study was to compare the potency, effectiveness and duration of action of synthetic bPTH-(1–34) with those of other known hypotensive peptides in the anesthetized dog. Of sixteen peptides tested in the present study only 8 were demonstrated to possess hypotensive activity. While bPTH-(1–34) was one of the least potent of the hypotensive peptides, it was equal to or greater than the other peptides in terms of effectiveness and duration of action. Of all the peptides studied, substance P and eledoisin were the most potent in terms of their hypotensive action. It is suggested that perhaps substance P and eledoisin might act at a different site or through different mechanisms than do vasoactive intestinal peptide (V.I.P.), corticotropin inhibiting peptide (C.I.P.), neurotensin, xenopsin, bradykinin and bPTH-(1–34). 相似文献
7.
Andréa N. M. Rangel da Silva Eduardo J. M. Nascimento Marli Tenório Cordeiro Laura H. V. G. Gil Frederico G. C. Abath Silvia M. L. Montenegro Ernesto T. A. Marques Jr. 《PloS one》2009,4(10)
Background
Dengue virus infection is a growing global public health concern in tropical and subtropical regions of the world. Dengue vaccine development has been hampered by concerns that cross-reactive immunological memory elicited by a candidate vaccine could increase the risk of development of more severe clinical forms. One possible strategy to reduce risks associated with a dengue vaccine is the development of a vaccine composed of selected critical epitopes of each of the serotypes.Methodology/Principal Findings
Synthetic peptides were used to identify B-cell epitopes in the envelope (E) glycoprotein of dengue virus type 3 (DENV-3). Eleven linear, immunodominant epitopes distributed in five regions at amino acid (aa) positions: 51–65, 71–90, 131–170, 196–210 and 246–260 were identified by employing an enzyme- linked immunosorbent assay (ELISA), using a pool of human sera from dengue type 3 infected individuals. Peptides 11 (aa51–65), 27 and 28 (aa131–150) also reacted with dengue 1 (DENV-1) and dengue 2 (DENV-2) patient sera as analyzed through the ROC curves generated for each peptide by ELISA and might have serotype specific diagnostic potential. Mice immunized against each one of the five immunogenic regions showed epitopes 51–65, 131–170, 196–210 and 246–260 elicited the highest antibody response and epitopes131–170, 196–210 and 246–260, elicited IFN-γ production and T CD4+ cell response, as evaluated by ELISA and ELISPOT assays respectively.Conclusions/Significance
Our study identified several useful immunodominant IgG-specific epitopes on the envelope of DENV-3. They are important tools for understanding the mechanisms involved in antibody dependent enhancement and immunity. If proven protective and safe, in conjunction with others well-documented epitopes, they might be included into a candidate epitope-based vaccine. 相似文献8.
During the past year, advances in our understanding of receptor–ligand interactions between opposing cell surfaces have occurred at a structural level. These include adhesion involving CD2–CD58, antigen-specific T-cell receptor interactions with peptides bound to major histocompatibility complex molecules (both pMHCI and pMHCII), the CD8αα co-receptor–pMHCI interaction and the binding of two distinct classes of natural killer receptors to self-MHC ligands. 相似文献
9.
Conformational change of bovine serum albumin by heat treatment 总被引:1,自引:0,他引:1
Kunio Takeda Akira Wada Kazuo Yamamoto Yoshiko Moriyama Koichiro Aoki 《Journal of Protein Chemistry》1989,8(5):653-659
The thermal denaturation of bovine serum albumin (BSA) was studied at pH 2.8 and 7.0 in the range of 2–65°C. The relative proportions of -helix, -structure, and disordered structure in the protein conformation were determined as a function of temperature, by the curve-fitting method of circular dichroism spectra. With the rise of temperature at pH 7.0, the proportion of -helix decreased above 30°C and those of -structure and disordered structure increased in the same temperature range. The structural change was reversible in the temperature range below 45°C. However, the structural change was partially reversible upon cooling to room temperature subsequent to heating at 65°C. On the other hand, the structural change of BSA at pH 2.3 was completely reversible in the temperature range of 2–65°C, probably because the interactions between domains and between subdomains might disappear due to the acid expansion. The secondary structure of disulfide bridges-cleaved BSA remained unchanged during the heat treatment up to 65°C at pH 2.8 and 7.0. 相似文献
10.
Neurotensin-like immunoreactivity in the nervous system of hydra 总被引:3,自引:0,他引:3
C. J. P. Grimmelikhuijzen R. E. Carraway Å. Rökaeus F. Sundler 《Histochemistry and cell biology》1981,72(2):199-209
Summary Neurotensin-like immunoreactivity is found in nerve fibers present in all body regions of hydra. The nerve fibers are especially numerous in the ectoderm at the bases of the tentacles and in the ectoderm at a site just above the foot. Radioimmunoassays of acetic-acid extracts of hydra, using various region-specific antisera towards mammalian neurotensin, show the presence of multiple neurotensin-related peptides. The amounts of these peptides vary between 1 and 350 pmol per gram wet weight. Gel filtration on Sephadex G-25 reveals a fraction of neurotensin-like peptides that crossreacts equally well with an antiserum directed against sequence 1–8 and an antiserum directed against sequence 6–13 of neurotensin. This fraction elutes also at the position of neurotensin and might closely resemble the mammalian peptide. A fraction eluting with the void volume crossreacts preferentially with antisera directed against sequences 1–8 and 10–13 of neurotensin. Several components of apparent lower molecular weight than neurotensin crossreact preferentially with an antiserum against sequence 10–13. These last peptides represent the major portion of the neurotensin-like peptides in hydra. 相似文献
11.
A 30-residue peptide was obtained from ribonuclease A by chemical cleavage with cyanogen bromide, subsequent sulfitolysis with concomitant S-sulfonation, and finally enzymatic cleavage withStaphylococcus aureus protease. The peptide was converted to the free thiol form by reductive cleavage of the S-sulfo-protecting groups withd,l-dithiothreitol. This peptide consisted of residues 50–79 of the native sequence of ribonuclease A, with the exception that methionine-79 had been converted to homoserine. Included in this sequence are residues cysteine-65 and cysteine-72, which form a disulfide bond in the native enzyme, as well as cysteine-58. This molecule may form one of three possible intramolecular disulfide bonds upon thiol oxidation, viz. one loop of 15 and 2 of 8 residues each. These isomeric peptides were prepared by oxidation with cystamine, 2-aminoethanethiolation of residual thiols, and fractionation by reverse-phase high-performance liquid chromatography. Disulfide pairings were established by mapping the tryptic fragments and confirming their composition by amino acid analysis. After protracted incubation under oxidizing conditions at 25.0°C andp H 8.0, the 26-member ring incorporating the native disulfide bond between residues 65 and 72 is the dominant product. Assuming that equilibrium is established, we infer that local interactions in the sequence of ribonuclease A significantly stabilize the native 8-residue disulfide loop with respect to the non-native 8-residue loop (G°=–1.1±0.1 kcal mole–1). The implications of this observation for the oxidative folding of the intact protein are discussed. 相似文献
12.
Eran J. Yavin Oren Rosen Michel Pontet Enid G. Shephard Mati Fridkin 《Letters in Peptide Science》1995,2(1):7-16
Summary Proteolysis of human C-reactive protein (CRP) by lysosomal enzymes derived from human neutrophils is shown to yield short peptides capable of modulating the production of superoxide ions by stimulated human neutrophils. Thus, fractionation of trichloroacetic acid-soluble digestion mixtures by HPLC yielded the following peptides: Ser-Tyr (1), Gly-Tyr (2), Phe-Glu-Val-Pro-Glu-Val-Thr (3), Trp-Asp-Phe-Val (4), Asn-Met-Trp-Asp-Phe-Val (5) and Gln-Leu-Trp-Pro (6). These peptides, corresponding to CRP sequences 18–19, 48–49 and/or 72–73, 84–90, 162–165, 160–165 and 203–206, respectively, have been synthesized and peptides 2, 3 and in particular peptide 6 were found to significantly inhibit neutrophilic function. The results suggest that CRP-derived peptides may be capable of regulating superoxide ion production by neutrophils in vivo during the acute phase response as part of a complex protective mechanism. 相似文献
13.
A. O. Shpakov V. I. Korol'kov E. N. Vlasova G. P. Vlasov 《Journal of Evolutionary Biochemistry and Physiology》2002,38(2):176-183
The signal transduction process via adenylyl cyclase system (ACS) requires coordinated functioning of signal proteins—components of ACS. It is suggested that functional coupling between them, together with other molecular mechanisms, is based on coiled-coil interactions. To study role of these interactions in functioning of ACS, we synthesized cationic coiled-forming peptides with a regular structure Ac–Ala–His– (Ala)2–His–Ala–NH2 (I), Ac–Ala–His–(Ala)3–His– (Ala)2–His–Ala–NH2 (II), and Ac–(Pro(2–His– (Ala)2–His– (Ala)2–His– (Ala)2–His–Ala–NH2 (III). Using circular dichroism (CD) spectroscopy, a portion of -helix conformation in their secondary structure was determined, and effects of these peptides on basal adenylyl cyclase (AC) activity as well as on the activity stimulated by non-hormonal (NaF and Gpp[NH]p) and hormonal (serotonin) agents was studied in homogenate of mouse fibroblasts, line L (subline LSM). The synthetic peptides were shown to inhibit in a dose-dependent manner both basal and induced AC activity, which indicates their uncoupling action on ACS. The biological effect of these peptides correlated with their length (I < II < III), but not with coiled-coil structure, which was 20, 7, and 21%, respectively, according to data of circular dichroism spectroscopy in 3-fluoroethanol. However, there are reasons to believe that the coiled-coil structure of peptides, first place extended ones, increases at interaction with plasma membrane and signal proteins, which affects the degree of their effect on functional ACS activity. At micromolar concentrations, peptides II and III were established to markedly stimulate the basal AC activity, thereby mimicking G-protein-binding sites of cytoplasmic receptor loops. The data obtained indicate participation of the coiled-coil interactions in functional coupling of ACS components, and the methodology itself of the use of model peptides with different coiled-coil structure and distribution of charged amino acids is an efficient approach for studying molecular bases for functioning of signal systems. 相似文献
14.
POMC-derived peptides and mRNA have been identified in heart tissue, although POMC processing has not been fully characterized. In the present study, we found that β-lipotropin and ACTH were localized in rat heart, although they were almost entirely converted to β-endorphin- and α-MSH-related peptides. Ion exchange HPLC analysis revealed that β-endorphin(1–31) was further processed to α-N-acetyl-β-endorphin(1–31), which comprised 35.9 ± 0.1% of total immunoreactivity, and smaller amounts of β-endorphin(1–27), β-endorphin(1–26), and their α-N-acetylated derivatives. The predominant α-MSH immunoreactive peptides coeluted with α-MSH and N,O-diacetyl-α-MSH by reverse-phase HPLC, although small amounts of ACTH(1–13)-NH2 were also present. Thus, multiple forms of β-endorphin and α-MSH are localized in rat heart. β-Endorphin(1–31) is a minor constituent, however, indicating that nonopioid β-endorphin peptides predominate. 相似文献
15.
Chen JM Friedman FK Brandt-Rauf PW Pincus MR Chie L 《Journal of Protein Chemistry》2002,21(5):349-359
GTPase activating protein (GAP) is a known regulator of ras-p21 activity and is a likely target of ras-induced mitogenic signaling. The domains of GAP that may be involved in this signaling are unknown. In order to infer which domains of GAP may be involved, we have performed molecular dynamics calculations of GAP complexed to wild-type and oncogenic (Val 12–containing) ras-p21, both bound to GTP. We have computed and superimposed the average structures for both complexes and find that there are four domains of GAP that undergo major changes in conformation: residues 821–851, 917–924, 943–953, and 1003–1020. With the exception of the 943–953 domain, none of these domains is involved in making contacts with ras-p21, and all of them occur on the surface of the protein, making them good candidates for effector domains. In addition, three ras-p21 domains undergo major structural changes in the oncogenic p21-GAP complex: 71–76 from the switch 2 domain; 100–108, which interacts with SOS, jun and jun kinase (JNK); and residues 122–138. The change in conformation of the 71–76 domain appears to be induced by changes in conformation in the switch 1 domain (residues 32–40) and in the adjacent domain involving residues 21–31. In an accompanying paper, we present results from microinjection of peptides corresponding to each of these domains into oocytes induced to undergo maturation by oncogenic ras-p21 and by insulin-activated wild-type cellular p21 to determine whether these domain peptides may be involved in ras signaling through GAP. 相似文献
16.
Dry matter and nutrient inputs through litter fall in a dry tropical forest of India 总被引:1,自引:0,他引:1
Lalji Singh 《Plant Ecology》1992,98(2):129-140
The present paper elucidates the pattern of leaf and non-leaf fall and quantifies of the total annual input of litter in a dry tropical forest of India. In addition, concentration of selected nutrients in various litter species and their annual return to the forest floor are examined. Total annual input of litter measured in litter traps ranged between 488.0–671.0 g m-2 of which 65–72% was leaf litter fall and 28–35% wood litter fall. 73–81% leaves fall during the winter season. Herbaceous litter fall ranged between 80.0–110.0 g m-2 yr-1. The annual nutrient return through litter fall amounted (kg ha-1): 51.6–69.6 N, 3.1–4.3 P, 31.0–40.0 Ca, 14.0–19.0 K and 3.7–5.0 Na, of which 71–77% and 23–29% were contributed by leaf and wood litter fall, respectively for different nutrients. Input of nutrients through herbaceous litter was: 13.0–16.6 for N, 1.0–1.4 for P, 4.0–5.0 for Ca, 7.9–10.5 for K and 0.8–1.0 kg ha-1 yr-1 for Na. 相似文献
17.
Bernard Rousset Chantal Poncet Rene Mornex 《Biochimica et Biophysica Acta (BBA)/General Subjects》1976,437(2):543-561
Isolated thyroid cells prepared from hog thyroid glands by tryptic dispersion were incubated with 131I− for 1–6 h. Free [131I]thyroxine was identified in the incubation medium by three chromatographic methods. Neither [131I]iodotyurosines nor [131I]triiodothyronine were detected. The [131I]thyroxine released in the medium by 100 μl of cells (packed cell volume) after a 6-h incubation period amounted to 1.16% (S.E. = ± 0.39) of the total radioactivity. The medium [131I]thyroxine represented 15–25% of the total [131I]thyroxine synthesized during the 6 h of incubation. Thyrotropin, 1–60 munits/ml, increased the medium [131I]thyroxine content 2–4 fold. Dibutyryl cyclic AMP mimicked the effect of thyrotropin. The amount of medium [131I]thyroxine was strictly related to the amount of incubated cells but was independent of the volume of the incubation medium. When prelabeled cells were incubated in the presence of methimazole the increase in medium [131I]thyroxine was quantitatively related to a decrease in the intracellular [131I]thyroxine. Addition of dinitrotyrosine, an inhibitor of the deiodinase activity, induced the release of iodotyrosines in the incubation medium. That the incubation supernatant of isolated thyroid cells did contain free thyroxine but no iodotyrosines suggests that the normal mechanisms of proteolysis of thyroglobulin and deiodination of iodotyrosines inside the cells are preserved. From these data, it was concluded that the thyroxine release by isolated cells represents a real secretion. 相似文献
18.
Five major endo-(1→4)-β-
-glucanases (I–V) have been isolated from a cellulase preparation of P. pinophilum. The pI values for I–V were 7.4, 4.8, 4.1, 3.7, and 4.0, respectively, and the respective molecular weights were 25,000, 39,000, 62,500, 54,000, and 44,500, when determined by SDS-gel electrophoresis. Endoglucanase V was optimally active at 65–70° and I–IV were most active at 50–60°. The pH optima of I and III–V were in the range 4.0–5.0. Antiserum prepared to I reacted only with I; II antiserum reacted only with II. Endoglucanases I and V were more random in their attack on CM-cellulose and H3PO4-swollen cotton cellulose, and showed no activity against cello-oligosaccharides containing less than five
-glucose residues, whereas III and IV were active against all the cello-oligosaccharides tested and acted in a less random manner, and II was intermediate in its catalytic action. III was adsorbed completely on both Avicel PH101 and H3PO4-swollen cellulose, whereas IV was not adsorbed. The endoglucanases I–V have distinct roles in the digestion of cellulose. 相似文献
19.
Chie L Chen JM Friedman FK Chung DL Amar S Michl J Yamaizumi Z Brandt-Rauf PW Pincus MR 《Journal of Protein Chemistry》1999,18(8):875-879
In the preceding paper we performed molecular dynamics calculations of the average structures of the SOS protein bound to wild-type and oncogenic ras–p21. Based on these calculations, we have identified four major domains of the SOS protein, consisting of residues 631–641, 676–691, 718–729, and 994–1004, which differ in structure between the two complexes. We have now microinjected synthetic peptides corresponding to each of these domains into Xenopus laevis oocytes either together with oncogenic (Val 12)-p21 or into oocytes subsequently incubated with insulin. We find that the first three peptides inhibit both oncogenic and wild-type p21-induced oocyte maturation, while the last peptide much more strongly inhibits oncogenic p21 protein-induced oocyte maturation. These results suggest that each identified SOS region is involved in ras–stimulated signal transduction and that the 994–1004 domain is involved uniquely with oncogenic ras–p21 signaling. 相似文献
20.
M. Zouhair Atassi C. Steven McDaniel Taghi Manshouri 《Journal of Protein Chemistry》1988,7(5):655-666
A set of seven peptides constituting the various loops and most of the surface areas of -bungarotoxin (BgTX) was synthesized. In appropriate peptides, the cyclical (by a disulfide bond) monomers were prepared. In all cases, the peptides were purified and characterized. The ability of these peptides to bindTorpedo californica acetylcholine receptor (AChR) was studied by radiometric adsorbent titrations. Three regions, represented by peptides 1–16, 26–41, and 45–59, were able to bind125I-labeled AChR and, conversely,125I-labeled peptides were bound by AChR. In these regions, residues Ile-1, Val-2, Trp-28 and/or Lys-38, and one or all of the three residues Ala-45, Ala-46, and Thr-47, are essential contact residues in the binding of BgTX to receptor. Other synthetic regions of BgTX showed little or no AChR-binding activity. The specificity of AChR binding to peptides 1–16, 26–41, and 45–59 was confirmed by inhibition with unlabeled BgTX. It is concluded that BgTX has three main AChR-binding regions (loop I with N-terminal extension and loops II and III extended toward the N-terminal by residues 45–47). 相似文献