摘要:

Bovine plasma albumin (BPA) has approximately one SH group (Cys‐34) which catalyzes the intramolecular SH, S‐S exchange reaction in the alkaline region at low ionic strength, resulting in the formation of the aged form. So, the N‐B transition at ionic strength above 0.20 and below 0.10 was studied using BPA and iodoacetamide‐blocked BPA (IA‐BPA), respectively. (1) pH profiles of [θ]262and[θ]268of BPA in 0.20mKCl showed the characteristic changes in the pH region 7.0‐9.0, corresponding to the N‐B transition. On going from pH 7.0 to 9.0 in 0.10 M KCl or NaCl, IA‐BPA did not show significant changes in rotational relaxation times of tryptophyl fluorophors, CD‐resolved secondary structures, spin‐echo1H‐n.m.r. spectra and cross‐relaxation times (T1S) between irradiated and observed protein protons, which might reflect the rigidity of the domains and/or subdomains. On the other hand, rotational relaxation times of l‐anilino‐8‐naphthalenesulfonate‐IA‐BPA complex (IA‐BPA‐ANS0 9, molar ratio of ANS to IA‐BPA = 0.9/1) showed significant decreases from 131 to 114ns on going from the N‐ to the B‐forms in 0.10M KCl. The above results and reported experimental evidence might indicate that on going from the N‐ to the B‐forms in 0.10mKC1 or NaCl, the mutual movement of subdomains, connected with a flexible hinge region (Brown&Shockley (1982)) might increase without loss in the helicity and the rigidity of subdomains. (2) The N‐B transition of IA‐BPA in the absence of salt was quite different from those in 0.10 M KCl or NaCl. Decreases in the helicity and the intramolecular rigidity, as monitored by TIS‐measurem

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00714.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Six proctolin analogues (I‐VI) modified in position 1 of the peptide chain by the following amino acids: homo‐Arg, Gac, Gav, Gap, Phe (p‐guanidino) and Orn, were synthesized by conventional liquid phase method. The myotropic activity of the obtained peptides was investigated in cardioexcitatory test on two insect species, cockroach,Periplaneta americanaL., and yellow mealworm,Tenebrio mo

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00715.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Escherichia colicells transformed with plasmids engineered for the expression of recombinant human growth hormone as a secreted product also produced a proteolytically cleaved form of rhGH. This variant is isolated at a high resolution anion exchange chromatography stage during the manufacturing process. The higher isoelectric point of this form is demonstrated by isoelectric focusing and chromatofocusing and the two‐chain nature by tryptic mapping,N‐ and C‐terminal sequence analyses, and sodium dodecyl sulfate polyacrylamide gel electrophoresis. These data indicate that the single site of cleavage is between Thr‐142 and Tyr‐143, in contrast to the two‐chain variant isolated from human pituitary glands, which has a clip after residue Phe‐139. The recombinant two‐chain form was further characterized by reversed‐phase high performance liquid chromatography at both acidic and basic pHs. The assay utilizing bicarbonate‐containing mobile phases was determined to be the most efficient and sensitive method. The bioactivity of this two‐chain form was measured by thein vivorat weight gain assay and by thein vitroNb2 cell bioassay. Its immunological similarity to intact one‐chain rhGH was demonstrated with an enzyme‐l

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00716.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The 7S globulin storage proteins, phaseolin, vicilin, and β‐conglycinin of, respectively, dry bean, field pea, and soybean, are highly homologous, have similar predicted protein structures, and yet exhibit considerable differences in their susceptibility to various proteinases [Nielsen, S.S., Deshpande, S.S., Hermodson, M.A.&Scott, M.P. (1988)J. Agric. Food Chem.36, 896‐902]. These differences in their proteolytic behavior were studied in relation to their solution conformational states. The secondary structures of these three proteins determined by far u. v. circular dichroism were characterized by predominantly β‐sheet and β‐turn parameters. However, characterization of tertiary and quaternary structures using second derivative u. v. absorption spectroscopy, surface hydrophobicity usingcis‐parinaric acid as hydrophobic probe, and fluorescence quenching studies of intrinsic Trp fluorescence using an ionic (iodide) and a neutral (acrylamide) quencher indicated sharp differences in the conformation of these proteins. About 9.6 and 10.2 out of 13 and 15 tyrosyls/subunit of phaseolin and β‐conglycinin, respectively, were exposed to polar solvent, while the surface hydrophobicity varied β‐conglycinin>vicilin>phaseolin. The Trp residues in phaseolin were not accessible to iodide, while half those of vicilin and β‐conglycinin were quenched. The order of Trp accessibility to acrylamide was vicilin>β‐conglycinin>phaseolin. The relative compactness of these three proteins based on these studies was related to the observed differences in their susceptibilit

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00717.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

As part of a program to study the structure‐activity relationship of peptide opioids we report the synthesis, conformational characterization and biological activity of four analogs related to morphiceptin in which the proline at position two has been substituted with 2‐aminocyclopentane carboxylic acid (βAc5c). The βAc5c residue is a beta amino acid with two chiral centers resulting in four possible configurations; two configurationalcis(R,S and S,R) and two configurationaltrans(R,R and S,S) forms. Utilizing high resolution n.m.r. at 500 MHz and computer simulations with NOE restraints the chirality of the βAc5c residues are assigned. The analog containing the R,S‐βAc5c is active at both the μ and δ‐opioid receptors, with a slight preference for the μ‐receptor. The (S,R), (S,S), and (R,R) analogs show minimal activity at the μ‐receptor and are inactive at the δ‐receptor. A comparison of the findings from the conformational analysis and biological assays lends insight into the structure‐activity relationship of this

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00718.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

On the basis of the observation that in the hormonotoxin oLH‐gelonin conjugation of the toxin occurs via the α‐subunit of lutropin, an attempt was made to develop a general method for generation of similar hybrid proteins involving other glycoprotein hormones. In this approach sites suitable for conjugation would be first introduced into the α‐subunit, hybridized with any native hormone specific β‐subunit of choice (LH‐β, FSH‐β, TSH‐β) following which the toxic component gelonin would be added on in the form of gelonin‐S‐S‐ α—β complex. Thus, thiolated lutropin α‐subunit recombined well with free lutropin β‐subunit, yielding a hybrid which was active in terms of receptor binding, immunoreactivity, and steroidogenic properties. However, subsequent conjugation with thiolated gelonin, a ribosome inactivating protein, resulted in dissociation of β‐subunit from its non‐covalent union with the thiolated α‐subunit. It is concluded that the addition of positively charged gelonin at particular sites on the α‐subunit led to the destab

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00719.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

2‐Oxazolidone derivatives formed through an intramolecular reaction in the process of alkaline treatment of urethane‐typeN‐protected peptides of which theN‐terminal residues were Ser or Thr having unprotected hydroxyl groups. In order to avoid this side reaction, the esters of these peptides could be cleaved by enzymatic hydrolyses instead of saponif

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00720.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Two cyclic tripeptide homologs, cyclo(Glu[Cys‐β‐Ala‐]‐OH) 8a, and cyclo(Glu[Cys‐Gaba‐]‐OH) 8b, were synthesized by the pentafluorophenyl ester method in solution (1‐3). These cyclic peptides are cyclo homologs of glutathione and are designed as potential antitumor agents. The1H‐ and13C‐n.m.r. spectral parameters of cyclo(Glu[Cys(Bzl)‐β‐Ala‐]‐OH) 7a were measured in DMSO‐d6and a possible conformation has been proposed. The cyclic peptide 8a showed low cytotoxic activities against three human tumor cel

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00721.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Chemical synthesis of large peptide fragments (from 18 to 66 amino acid residues long) of the gp110 envelope glycoprotein and ofnef‐protein from HIV‐1 was achieved by the solid phase method. Stepwise assembling of the peptide chains was carried out automatically on 4‐(oxymethyl)‐phenylacetamidomethyl resin using the N‐α‐butyloxycarbonyl amino acids with benzyl‐based side chain protecting groups. Two elongation protocols were used depending on the peptide chain length: a standard cycle, mainly characterized by a single coupling step (Boc‐amino acid symmetrical anhydride in dimethylformamide), and an optimized one for large peptides, based on a double coupling strategy (Boc‐amino acid symmetrical anhydride first in dimethylformamide, then in dichloromethane). Final cleavage of the peptide from the solid support was carried out by anhydrous hydrogen fluoride and crude peptides were purified by C18reverse phase medium pressure liquid chromatography after molecular filtration. Characterization of the purified peptides was done by analytical HPLC, amino acid content determination, and circular dichroism analysis both in polar (H2O) and in non‐polar (TFE) environments. Immunoreactivity of anti‐nefpositive sera from HIV‐1 infected patients by ELISA with the synthetic peptides was investigated. The results showed four major antigenic regions ofnef‐protein and mainly the immunodominance of theN‐andC‐termini of the molecule. Several of these peptides should prove to be useful for both diag

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00722.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Solid phase synthesis of the hexapeptide, GPRVVE, which represents the amino terminal six amino acids of the α‐chain of human fibrin, yielded a product that contained a modified glutamic acid. The nature of the modification was established as the Friedel‐Crafts acylation product of the peptide and anisole, the latter reagent employed in the HF deblocking step. The anisoylated peptide selectively enhanced the activation rate of native [Glu1]plasminogen by recombinant tissue plasminogen activator, accelerated clot lysis, and retarded the polymerization of nascent f

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb00723.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY