摘要:

Detailed conformational studies in the solid and solution state have been carried out on the blocked peptidetert.‐butyloxycarbonyl‐L‐aminosuccinyl‐glycyl‐glycine methyl ester, a model compound to study the conformational restrictions imposed by the presence of an aminosuccinyl residue in a polypeptide chain.The crystals belong to the monoclinic space group P21witha= 5.022(1),b= 15.193(3),c= 11.173(2) Å, β = 95.09(1)± andV= 849.0(5) Å3. The structure was solved by direct methods and least‐squares refinement, which included the coordinates of hydrogen atoms, converged at R = 0.030 for 1648 *** reflections. Although in the solid state the molecule prefers an ***extended ***mation, the i.r. and1H n.m.r. spectra in chloroform solution *** that a folded conformation of the type II′ β turn, also predicted by the potential energy calcu

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00932.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Gel‐exclusion high‐performance liquid chromatographic (HPLC) analysis of human serum albumin (HSA) on PGP 2000 column (0.10 M sodium phosphate buffer, 0.30 M NaCl, pH 6.86) showed at least two peaks, the principal component corresponding to human mercaptalbumin (HMA) and the second one to human nonmercaptalbumin (HNA). Mechanism for the separation of HMA and HNA might be due to weak resin‐HSA interaction. HPLC analysis of bovine plasma albumin (BPA) showed a single peak on PGP 2000 column. The elution volume of HSA was larger than that of BPA, resulting in a clear resolution of HSA an

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00933.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The recently introduced fast protein liquid chromatography (FPLC) system of Pharmacia (Uppsala, Sweden) was employed to isolate rather large peptides derived from thermolysin by selective chemical fragmentation at methionine in positions 120 and 205 of the polypeptide chain of 316 amino acid residues. Thermolysin was cleaved under conditions of limited fragmentation in order to produce, besides fragments 1–120, 121–205 and 206–316, the overlapping fragments 1–205 and 121–316. These polypeptides were separated employing prepacked Mono Q or Mono S columns (quaternary ammonium and sulfonic acid support, respectively). The columns were equilibrated with acetate‐7 M urea buffer, pH 5.0 or 6.0, and eluted with a gradient of sodium chloride or acetate. Separations were achieved in 10–20 min and were carried out also at a semipreparative level (1–3 mg per run). All five protein fragments were isolated in homogeneous form, as judged by amino acid analysis and electrophoresis. Considering that protein fragmentation with cyanogen bromide is the most commonly used procedure to achieve selective chemical fragmentation of a polypeptide chain, these results indicate that FPLC with ionic exchangers can be usefully employed to isolate rather large protein fragments especially suitable for automatic sequence analysis with

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00934.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A simple, rapid method is described for the purification of radioiodinated peptides for use in radioimmuno‐ and in radioreceptor assays. Iodinated reaction mixtures are applied directly onto Sep‐Pak® disposable, reversed phase cartridges equilibrated with phosphate buffer. Unreacted 125‐iodide and other non‐peptide reaction components are eluted with buffer. The peptide fraction is then eluted with 70% buffer:30% acetonitrile. The peptide fraction is further purified by reversed phase high pressure liquid chromatography to separate the native peptide and the mono‐ and diiodo‐derivatives. In this study the method is used to prepare 125‐iodide‐labeled monoiodo‐leucine enkephalin and monoiodo‐angiotensin II, which are free of the parent peptides and diiodo‐derivatives and are of maximum obtainable specific radioactivity. The usefulness of these labeled peptides in radioimmuno‐ and radioreceptor assays is demonstrated by their binding to specific antibodies and

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00935.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The tripeptide, glycyl‐glycyl‐L‐isoleucine, crystallizes as a monohydrate in the monoclinic space group P21, with a = 12.746(2), b = 6.172(1), c = 8.643(1) Å, β = 99.77(2)°, and Z = 2. The structure was solved by direct methods and refined to an R‐value of 0.039 for 917 (I>1°) reflections. The molecule exists as a zwitterion in the crystal. The peptide units are trans and show significant deviations from planarity. The plane of peptide units and of the carboxyl group are nearly mutually perpendicular to each other. The peptide backbone torsion angles are: ø1= ‐ 171.2°, ω1= ‐ 176.8°, ø2= ‐ 106.1°, ø2= ‐ 150.7°, ø2= ‐ 172.1°, ø3= ‐ 70.9°, ø3= 136.5°. For the side‐chain of isoleucine, ø1= ‐ 58.1°, ø2= 169.7° and the system of bonds C′‐Cα‐Cβ‐C γ1‐Cδ is trans zig‐zag. The packing arrangemen

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00936.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The conformational properties of Boc‐Leu3‐(Pro2GlyLeu3)n‐Pro2Gly‐OH(n = 0, 1, 3, and 5) and Boc‐Leu3‐(Pro2GlyLeu3)n‐Pro2Gly‐OBzl (n = 7, 9, and 11) were investigated in various organic solvents of high polarity using molar rotation and CD measurements. The peptides examined are assembled by theN‐terminal, internal, andC‐terminal segments having the sequences of Boc‐Leu3, Pro2Gly‐Leu3, and Pro2Gly‐OX (X = H or Bzl), respectively. The conformational studies using the molar rotation of the oligopeptides and polypeptides in MeOH, DMSO, DMF, DMA, and NMP have made it clear that all the peptides have a randomly coiled structure. CD spectral patterns of the peptides in MeOH were essentially the same as each other and indicative of the randomly coiled structure. The additive nature of the total molar rotation and total molar ellipticity in Boc‐Leu3‐(Pro2GlyLeu3)n‐Pro2Gly‐OX (X = H or Bzl) indicates that the “peptide segment separation” is indeed in operation in organic solvents of high polarity and that the peptide molecule can be considered to be assembled with the small peptide segmen

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00937.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The tripeptide Boc‐Aib‐Leu‐Pro‐NHMe crystallizes in the orthorhombic space group P212121with a = 9.542, b = 15.200, c = 18.256 Å and Z = 4. Each peptide is associated wth two water molecules in the asymmetric unit of the crystal. The structure has been solved by direct methods and refined to an R‐value of 0.069. The peptide adopts a structure without any intramolecular hydrogen bond. The three residues occupy distinctly different regions of the Ramachandran map: Aib in the left‐handed 310‐helical region (± = 67°, ± = 23°), Leu in the β‐sheet region (± = ‐ 133°, ± = 142°) and Pro in the poly (Pro) II region (± = ‐ 69°, ± = 151°). An interesting observation is that each water molecule participates in four hydrogen bonds with distorted tetrahedral c

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00938.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

β‐Endorphin‐like immunoreactivity in whole brains of Sprague‐Dawley rat fetuses of different gestational ages was measured by radioimmunoassay and found to increase throughout the gestational period studied. The immunoreactivity in various brain parts (forebrain, midbrain, hindbrain, hypothalamus and pituitary) of late prenatal, early postnatal, young mature and retired breeder rats was also determined. In all the brain parts studied, a maximum in the content and concentration of β‐endorphin‐like immunoreactivity was attained when the rats were about 3

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00939.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Thermal denaturation for the wild‐type of tryptophan synthase α‐subunit fromE. coliand one of its mutant proteins was followed by CD measurements at various pHs in the alkaline region and the results from van't Hoff analyses of the thermal denaturation curves were compared with those from calorimetry. Although the far‐u.v. CD spectra of the thermally denatured proteins differed from those of the completely denatured states in 3.2 M guanidine hydrochloride, the titration curves by denaturants at higher temperatures were not sigmoidal but straight lines, indicating that the cooperative structure of the proteins has been completely destroyed by heating. The ratio of calorimetric enthalpy change to van't Hoff enthalpy change obtained from calorimetric study was unity, indicating that the thermal denaturation of the proteins was a two‐state system. The unfolding heat capacity change (ΔCp) of the wild‐type protein from van't Hoff analysis of the thermal denaturation curves by CD measurement was estimated to be 2.45 kcal/mol ± deg, which was similar to that from calorimetry. The values of unfolding enthalpy change at denaturation temperatures were lower by about 15 kcal/mol compared to those from

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00940.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Syntheses by solution methods of tryptophyllins ‐4 and ‐5 (TPH‐4 and TPH‐5), tetra‐ and pentapeptides isolated from the skin extracts of the South American frogPhyllomedusa rhodei, are reported. The incorporation of the Pro2‐Pro3sequence into pentapeptides and the use of flash chromatography for purification of intermediates and target compounds are discussed. Preliminary biological results seem to indicate a growth‐promoting activity for this p

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1984.tb00941.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY