摘要:

We report the synthesis of a new reagent for the introduction of an oxidative iodination site into the amino terminus of acid‐labile peptides, and the use of this reagent to synthesize a novel affinity‐labeling probe for the cholecystokinin (CCK) receptor. The acylation reagent,N,O‐bis‐fluorenylmethyloxycarbonyl‐d‐tyrosine hydroxysuccinimide ester, utilizes base‐labile protection of both the alpha amino group and the aromatic ring hydroxyl. This can be safely removed to expose a cross‐linkable free amino group on the aminopeptidase‐resistantd‐enantiomer of tyrosine. The synthetic probe,d‐Tyr‐Gly‐Asp‐Tyr(OSO3H)‐Nle‐Gly‐Trp‐Nle‐Asp‐Phe‐NH2, was fully biologically active, could be radioiodinated to high‐specific radioactivity (2000 Ci/mmol), bound with high affinity to the pancreatic CCK receptor, and covalently labeled the hormone‐binding site. This reagent should be useful for the synthesis of a wide variety of an

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00899.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

High‐performance liquid chromatographic (HPLC) analysis of human serum albumin (HSA) on Asahipak GS‐520 showed at least two peaks, the principal component corresponding to human mercaptalbumin (HMA) and the secondary one to nonmercaptalbumin (HNA). HPLC analysis of HSA on Asahipak ES‐520 N showed three peaks, the principal component corresponding to HMA, the secondary one to HNA having mixed disulfide with cysteine or glutathione and the tertiary one to HNA oxidized higher than mixed disulfide. Two kinds of rapid HPLC for the resolution of HSA into HMA and HNA were developed by the present authors. Using these HPLC, the present authors found a significant decrease in the fraction of HMA in the el

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00900.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Racemization attending the aminolysis of symmetrical (Sy) and mixed (Mx) anhydrides (An) ofN‐alkoxycarbonylamino acids by amino acid anions in aqueous dimethylformamide has been examined by reversed phase high‐performance liquid chromatography analysis of theN‐protected dipeptides produced. Racemization occurred in most cases when the anion was generated using 1 equiv. sodium hydrogen carbonate, in most cases for MxAn reactions when the base was sodium carbonate, and only in a few cases for SyAn reactions when the base was sodium carbonate. Less racemization was associated with MxAn reactions when the chloroformate of a secondary alcohol had been used for their generation. The change in chirality is explained on the basis of the formation and racemization of the 2‐alkoxy‐5(4H)‐oxazolone, which is greater in the presence of the weaker base because of incomplete deprotonation of the amino acid

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00901.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The crystal structure of a conformationally restricted cyclotripeptide containingN‐methylanthranilic acid,l‐phenylalanine andl‐proline has been determined. The 10‐membered ring ofcyelo(‐MeAnt‐Phe‐Pro‐) is characterized by a pseudosymmetry plane and by threecisamide bonds. The MeAnt aromatic ring makes an angle of 63.3° with the best plane of the backbone and is nearly perpendicular to the plane of the two adjacent amide bonds. The proline ring adoptsβαT twist conformation (Ps = 144°) and the benzylic side chain is extended towards the nitrogen. An analysis of i.r. and n.m.r. spectral data indicates that the solution conformation retains the features found in the crystals. Crystal data: orthorhombic, P212121witha= 10.153(3),b= 11.700(3),c= 16.402(3) Å and Z = 4. The final R and Rware 0.047 and

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00902.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Insulin has been isolated from ostrich pancreas by a procedure of acid ethanol extraction, adsorption onto SP‐Sephadex, gel permeation chromatography and HPLC. The primary structure of the ostrich insulin is identical to that reported for the chicken hormone. The isoelectric point as determined by polyacrylamide gel isoelectric focusing was significantly higher than that of the bovine hormon

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00903.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Five proctolin analogues modified in position 1 of the peptide chain by Cit (I), Lys (II), His (III), Phe(p‐NH2) (IV) and γ‐Abu (V) were synthesized by conventional liquid phase method. Biological activity of the obtained peptides was investigated by the cardioexcitatory test on two insect species, cockroach,Periplaneta americana L.and yellow mealworm,Tenebrio molit

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00904.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Secondary structure of interleukin‐2(Alal25) in unfolded state was examined by circular dichroism (CD). Unfolding of tertiary structure of the protein, as determined by CD, was observed when the solvent pH was decreased below 3.0 or the disulfide bond was reduced. Consistent with the CD results, a stronger fluorescence enhancement of 1‐anilinonaphthalene‐8‐sulfonic acid was observed on acidification or reduction of interleukin‐2(Alal25) relative to that of the native protein, indicating a larger hydrophobic surface exposed to solvent. However, the secondary structure was fully retained in 5% acetic acid or aqueous HCl, pH 3.0. It seemed that α‐helical content of the protein is even greater at pH 2.0. Reduced protein showed a far u.v. CD spectrum indistinguishable from the oxidized one at pH 4.0. These results suggest that the secondary structure of interleukin‐2(Alal25) does not require tert

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00905.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Different synthetic strategies have been attempted for the synthesis of a glycosylpeptide resulting from the covalent bonding of a sugar residue to theC‐terminal carboxyl group of an enkephalin related pentapeptide. The final structure is: Tyr‐d‐Met‐Gly‐Phe‐Pro [N15‐β‐d‐glucopyranosyl] amide. Thein vitropotency on the GPI test of this analogue was IC50= 64.0 nm. However, its antinociceptive activity by tail immersion tests, after intraperitoneal administration, was 2000 and 200 times higher than morphine in rats and

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00906.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Six cyclic retro‐analogues of the peptide hormone somatostatin have been synthesized using the solid phase technique. The peptides cyclo(‐Xaa1‐Phe2‐Thr3‐Lys4‐Ybb5‐Phe6‐) and cyclo(‐Phe1‐Xaa2‐Thr3‐Lys4‐Ybb5‐Phe6‐) with Xaa =d‐ orl‐Pro and Ybb =d‐ orl‐Trp were cyclized via the azide method. The conformations of the cyclic hexapeptides in DMSO‐d6solution were determined by a number of homo‐ and heteronuclear two‐dimensional n.m.r.‐techniques including 2D rotating frame NOE‐spectroscopy. Two‐step coherence transfers, ROE and chemical exchange, are observed for the first time in ROESY spectra. The backbone conformation of the all‐transcyclopeptides consists of aβ‐turn containing the Pro residue in the position i + 1. These retro‐analogues of somatostatin exhibit a high activity in the inhibition of cholate and phalloidin uptake by liver cells (cytoprotective effect); however, the hormonal activities of the natural hormone are completely suppressed. The constitutional and conformational re

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00907.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The synthesis of some [Leu5]enkephalin derivatives is described in whichd‐glucose has been linked to the opioid pentapeptide through the ester bond involving the carboxyl function at theC‐terminal with C‐1 or C‐6 of thed‐glucopyranose moiety. Enkephalin derivatives were assayed for opioid activity and found to be full agonists in bioassays based on inhibition of electrically evoked contractions of the guinea pig ileum (GPI) and of the mouse vas deferens (MVD). The obtained results suggest that the opioid activity of the tested glucoconjugates depend upon the ester bond position in the molecule. Whereas 1‐Oconjugate5was somewhat more potent than [Leu5]enkephalin in the GPI assay, the 6‐Oconjugates, with the exception of 1‐O‐benzyl derivative11, were considerably less potent. All enkephalin derivatives were δ‐receptor selective; in particular, the acetylated analog8was three times more δ‐receptor selectiv

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1988.tb00908.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY