Chromatographic separation and mass spectrometric identification of positional isomers of polyethylene glycol-modified growth hormone-releasing factor (1-29)

A one-step chromatographic method capable of separating all isomers of polyethylene glycol (PEG)-growth hormone-releasing factor (GRF) (1-29) conjugates was developed. The unmodified GRF (1-29) and seven different isomers of PEG-GRF (1-29) conjugates were separated by using a simple reversed-phase HPLC method depending on the differences of hydrophobicity due to the number and site of PEG attachment. The PEGylation sites of all isomers of PEG-GRF (1-29) conjugates were identified by determining the molecular masses of the Lys-C digested fragments with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This study is a first report for the separation of all PEG-conjugate isomers and would be useful for further studies to find the promising conjugate by evaluating biological activity and stability of each isomer.     

Purification and modification by polyethylene glycol of a new human basic fibroblast growth factor mutant-hbFGF(Ser25,87,92)

The mutant of human basic fibroblast growth factor (hbFGF), hbFGF(Ser25,87,92), which was constructed by replacing the cysteine residues at the positions of the 25th, the 87th and the 92nd with serine residues, was coupled to polyethylene glycol (PEG) with a molecular size of 20 kDa (20K) (PEG(20K)) to obtain hbFGF derivative, PEG(20K)-hbFGF(Ser25,87,92). The optimal modified reaction was conducted at 12 degrees C for 12h with the molar ratio of PEG(20K) to hbFGF(Ser25,87,92) of 30:1. The result of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that the modification rate was up to 60%. The PEGylated product retained binding affinity to heparin and could be purified by heparin affinity chromatography. Compared to hbFGF mutant, purified PEG(20K)-hbFGF(Ser25,87,92) retained about 34% of mitogenic activity. Heat-stability assay indicated that the modified product was more stable than the native protein at the temperature of 37 degrees C.     

Formation and structure elucidation of two novel spiro[2H-indol]-3(1H)-ones

The molecular structures of two byproducts 1,1'-diphenyl-3',4'-dihydrodispiro[indole-2,2'-furan-5',2'-indole]-3,3'(1H, 1'H)-dione (3) and 1,5'-diphenyl-4',5'-dihydro-3'H-spiro[indole-2,2'-pyrano[3,2-b]indol]-3(1H)-one (4), which accompanied the rearrangement of 3-hydroxy-3-methyl-1-phenylquinoline-2,4(1H,3H)-dione (1) to 2-hydroxy-2-methyl-1-phenyl-1,2-dihydro-3H-indol-3-one (2), have been elucidated by NMR, MS, and X-ray diffraction.     

Mixed micelles of polyethylene glycol (23) lauryl ether with ionic surfactants studied by proton 1D and 2D NMR

(1)H NMR chemical shift, spin-lattice relaxation time, spin-spin relaxation time, self-diffusion coefficient, and two-dimensional nuclear Overhauser enhancement (2D NOESY) measurements have been used to study the nonionic-ionic surfactant mixed micelles. Cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) were used as the ionic surfactants and polyethylene glycol (23) lauryl ether (Brij-35) as the nonionic surfactant. The two systems are both with varying molar ratios of CTAB/Brij-35 (C/B) and SDS/Brij-35 (S/B) ranging from 0.5 to 2, respectively, at a constant concentration of 6 mM for Brij-35 in aqueous solutions. Results give information about the relative arrangement of the surfactant molecules in the mixed micelles. In the former system, the trimethyl groups attached to the polar heads of the CTAB molecules are located between the first oxy-ethylene groups next to the hydrophobic chains of Brij-35 molecules. These oxy-ethylene groups gradually move outward from the hydrophobic core of the mixed micelle with an increase in C/B in the mixed solution. In contrast to the case of the CTAB/Triton X-100 system, the long flexible hydrophilic poly oxy-ethylene chains, which are in the exterior part of the mixed micelles, remain coiled, but looser, surrounding the hydrophobic core. There is almost no variation in conformation of the hydrophilic chains of Brij-35 molecules in the mixed micelles of the SDS/Brij-35 system as the S/B increases. The hydrophobic chains of both CTAB and SDS are co-aggregated with Brij-35, respectively, in their mixed micellar cores.     

Mannich reaction on 2-(2-benzofuranyl)-1H-indole. Determination of structure by NMR spectroscopic techniques

Analysis of the product from the Mannich reaction of 2-(2-benzofuranyl)-1H-indole via ¹H and ¹³C nmr spectroscopy was performed. The studies included use of Pr(Fod)₃ shift reagent, proton-coupled ¹³C spectra, deuterium isotope induced shifts and protonation studies. It was found that the reaction occurred on the indole moiety at C-3.     

Synthesis,structure, and properties of 1-(p-R-phenacyl)-2-(p-methoxybenzylamino)pyridinium bromides

We have synthesized 2-(p-methoxybenzylamino)-1-(p-R phenacyl)pyridinium bromides by alkylation of 2-R-(Pmethoxybenzylamino)pyridine with substituted phenacyl bromides. Using spectral methods we have shown that the title compounds exist in the form of 1, 2-diaryl-2-hydroxy-2, 3-dihydroimidazo[l, 2-alpyridinium salts. We have studied their properties and suggest an alternative synthesis route.T. G. Shevchenko Chernigov Pedagogical Institute, Chernigov 250038; Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev 252660. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 644-649, May, 1995. Original article submitted December 27, 1994; revised, April 20, 1995.     

Silylotropy and the29Si NMR spectrum of 2-[dimethyl(pentafluorophenyl)siloxy]-2-penten-4-one

Conclusions ¹H,¹³C, and²⁹Si NMR spectroscopy was used to study the structure and silylotropy of 2-[dimethyl(pentafluorophenyl)siloxy]-2-penten-4-one. The temperature dependence of the²⁹Si NMR chemical shifts indicated the existence of an intermediate with pentacoordinated silicon.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1424–1425, June, 1986.     

1-(2′-triethylsilylethyl)-, 1-(2′-triethylsilylvinyl)-, and 1′-(2′-triethylsilylethynyl)-silatranes

Conclusions The reaction of 2-triethylsilyl-substituted ethyl-, vinyl-, and ethynyltrialkoxysilanes with triethanolamine gave 1-substituted silatranes possessing neurotropic activity.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2611–2613, November, 1984.     

Synthesis and NMR elucidation of four novel 2-(trimethylsilyl)ethyl glycosides

Four novel 2-(trimethylsilyl)ethyl glycosides have been synthesized by a short and efficient route starting from d-glucose. Their structures were elucidated by applying high-resolution mass spectra, and one-dimensional and two-dimensional NMR techniques. These glycosides were prepared and used as intermediate building blocks in the scheme developed for oligosaccharide construction.     

Synthesis and properties of 1-(2-bromoethyl)-, 1-(2-alkoxyethyl)- and 1-(2-dialkylaminoethyl)2-alkylpyrroles

The reaction of 3-chloropropenyl alkyl ketones or 2,3-dichloropropyl alkyl ketones with 2-substituted ethylamine derivatives leads to the formation of the hitherto unknown 1-(2-R-ethyl)-2-alkylpyrroles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1047–1049, August, 1990.     

(Z)-1-[2-(二苯基碘化锡基)乙烯基]-1-环己醇的合成、晶体结构和性质

报道了标题化合物的合成、晶体结构及性质。该晶体属于单斜晶系，空间群为P2~1，晶胞参数a=0.9255(3)nm，b=1.0504(3)nm，c=1.0217(3)nm，β=100.99(2)°，V=0.9750nm^3，Z=2，D~c=1.790g/cm^3，R=0.025，晶体结构由直接法解出。标题化合物分子中的锡原子被配体的三个碳、一个碘和一个氧原子配位；配位原子是畸变的三角双锥构型；标题化合物具有与卤素发生取代反应而不发生加成反应的性质。     

PMR spectral study of the structure of 1-vinyl-2-(2-furyl)- and 2-(2-thienyl)pyrroles

Conclusions PMR spectral data indicate that the heterocycles in 1-vinyl-2-(2-fury1- and 1-vinyl-2-(2-thienyl) pyrroles lie in a single plane with syn arrangement of the heteroatoms and trans orientation of the vinyl group relative to the non-pyrrole heterocycle. Molecular coplanarity is lost in 3-alky1-1-vinyl-2-(2-furyl)- and 3-alkyl-1-vinyl-2-(2-thienyl) pyrroles.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 184–186, January.