Analysis of carbohydrates in glycoproteins by high-performance liquid chromatography and high-performance capillary electrophoresis

We describe two methods for the analysis of oligosaccharide chains in glycoproteins by high-performance liquid chromatography (HPLC) and high-performance capillary electrophoresis (HPCE).O-andN-glycosidically linked oligosaccharides released from glycoproteins can be identified as their borohydride-reduced forms by anion-exchange HPLC with pulsed amperometric detection.N-Glycosidically linked oligosaccharides can also be analyzed as 2-aminopyridine derivatives by HPCE in direct zone electrophoresis mode in an acidic phosphate buffer and zone electrophoresis mode as borate complexes in an alkaline buffer. We also present a convenient procedure for the analysis of the constituent monosaccharides of these oligosaccharides chains by HPLC based on reversed-phase partition mode as 1-phenyl-3-methyl-5-pyrazolone derivatives.     

Imaging mass spectrometry distinguished the cancer and stromal regions of oral squamous cell carcinoma by visualizing phosphatidylcholine (16:0/16:1) and phosphatidylcholine (18:1/20:4)

Most oral cancers are oral squamous cell carcinoma (OSCC). The anatomical features of OSCC have been histochemically evaluated with hematoxylin and eosin. However, the border between the cancer and stromal regions is unclear and large portions of the cancer and stromal regions are resected in surgery. To reduce the resected area and maintain oral function, a new method of diagnosis is needed. In this study, we tried to clearly distinguish the border on the basis of biomolecule distributions visualized by imaging mass spectrometry (IMS). In the IMS dataset, eleven signals were significantly different in intensity (p?<?0.01) between the cancer and stromal regions. Two signals at m/z 770.5 and m/z 846.6 were distributed in each region, and a clear border was revealed. Tandem mass spectrometric (MS/MS) analysis identified these signals as phosphatidylcholine (PC) (16:0/16:1) at m/z 770.5 in the cancer region and PC (18:1/20:4) at m/z 846.6 in the stromal region. Moreover, the distribution of PC species containing arachidonic acid in the stromal region suggests that lymphocytes accumulated in response to the inflammation caused by cancer invasion. In conclusion, the cancer and stromal regions of OSCCs were clearly distinguished by use of these PC species and IMS analysis, and this molecular identification can provide important information to elucidate the mechanism of cancer invasion.     

Chromatographic resolution of the enantiomers of a pharmaceutical intermediate from the milligram to the kilogram scale.

The preparative chromatographic resolution of racemic mixtures is rapidly becoming a standard approach for the generation of enantiomers in pharmaceutical R&D. This paper will discuss the optical resolution of a pharmaceutical intermediate as the separation is scaled up from the milligram to the kilogram scale. Difficulties encountered and their solutions at each scale will be discussed. In addition, the exploration of Simulated Moving Bed (SMB) for the separation will also be discussed. Finally, a comparison of the productivities and solvent consumption for each method and scale will be presented.     

Glycosides of 14,15-seco- and 13,14:14,15-disecopregnanes from the roots of Tylophora tanakae.

Five new glycosides of 14,15-seco- and 13,14:15-diseco-type pregnanes, including a new pregnane, 2 alpha-hydroxyhirundigenin, were isolated, in addition to one known glycoside, cynatratoside B, from the roots of Tylophora tanakae Maxim. Their structures were elucidated by spectral and chemical means.     

Thermal properties and solubility of poly-1,4,5,8-naphthalenetetracarboxydiimides containing 1,3,5-triazine rings

Aromatic polyimides were synthesized by polymerization of 1,4,5,8-naphthalenetetracarboxylic dianhydride and 2-dialkylamino-4,6-dihydrazino-1,3,5-triazines by a solution polymerization method followed by cyclodehydration. The polyimides had number-average molecular weights over 13,000–16,000 or viscosity values of 0.23–0.65 dl/g. The x-ray diffraction diagram of polyimide I showed a crystal pattern, but the pattern became less pronounced with increasing length of the polymer side chain, and thus polyimide V showed a typical amorphous pattern. Study of the thermal stability of the polyimides by thermogravimetric analysis showed that a steep weight loss occurred in the range 380–410°C. Among the polyimides, I had only poor solubility in organic solvent, while IV and V were soluble even in general organic solvents such as tetrahydrofuran and dioxane.     

The N—H stretching vibrations and conformations of trialkylthioureas

The ν(N-H) vibrations of trialkylthioureas observed in the dilute solutions are interpreted in relation to the trans—out isomerism. Occurrence of the out form is discussed from the point of view of steric hindrance. The two forms are characterized by the behavior of ν(N—H) vibrations at several concentrations. Solid DiPTUtB and DcHTUtB exhibited one sharp band at the same position as the ν(N—H) band in solution. This indicates that they are in the out form in the solid state as well as in solution.     

Conformations and steric and stacking interactions of trisubstituted ureas and thioureas with alkyl and phenyl groups

The monomeric ν(N—H) vibrations of various trisubstituted ureas of the R₂UPh type and -thioureas of the R₂TUPh type have been studied. The trans—out isomerism in the former and the trans—out—cis isomerism in the latter are discussed from the point of view of steric effect. The monomeric ν(N—H) vibrations of RPhUPh and RPhTUPh are also examined. The single band appearing in the spectrum of both ureas is characteristic of the cis form; this suggests the existence of phenyl—phenyl interaction (the stacking interaction proposed by Galabov et al. [10]). Behavior of ν(N—H) vibrations at several concentrations is shown to be clearly different in the three forms (trans, out and cis). The presence of the cis form is confirmed by solvent effect experiments.     

Simultaneous measurements of stress and infrared dichroism on polymers

Summary In order to obtain informations on the molecular nature and mechanism of rheological processes on polymers, simultaneous measurements of stress and infrared dichroism were made of polychloroprene (Neoprene Type AC) films during the course of continuous elongation at the constant rate 25%/min and of stress relaxation at 400% elongation. The time dependence of the infrared dichroism was obtained by measuring the intensity change at fixed wavenumbers of absorption band maxima on the differential polarized infrared spectra. Both the degree of crystallinity of sample films and the orientation function of transition moments were calculated from the results of the infrared dichroic measurements under the assumption of uniaxial orientation, which was confirmed to be the case by X-ray diffraction and birefringence measurements.In the continuous elongation experiments, it was found that the orientation functions for crystalline-sensitive bands showed maxima at 25% elongation and then decreased rapidly, changing their signs from positive to negative. There also appeared the yield point in the stress-strain curve and the beginning of sharp decrease of crystallinity at the same degree of elongation 25%. These facts were interpreted in terms of the orientation of the crystalline phase followed by the degradation of crystallites and drawing out of the molecular chain from the crystallites. In the stress relaxation experiments, moderate changes in the orientation functions were found for various characteristic absorption bands. Little difference was observed between changes in the orientation functions for the amorphous and crystalline-sensitive bands. This makes a contrast with the previous results for vulcanized natural rubber, where the orientation of the crystalline phase was completed almost immediately after elongation, while in the amorphous phase the molecular chains were oriented gradually during the course of stress relaxation.

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Zusammenfassung Um Informationen über die molekulare Natur und den Mechanismus rheologischer Prozesse von Polymeren zu erhalten, wurden gleichzeitige Messungen der Spannung und des Infrarot-Dichroismus an Polychloropren-Filmen (Typ AC-Neopren) während der kontinuierlichen Verstreckung bei konstanter Verstreckungsgeschwindigkeit von 25%/min und während der Spannungsrelaxation bei 400% Verlängerung durchgeführt. Die Zeitabhängigkeit des Infrarot-Dichroismus wurde aus der Intensitätsänderung im festen Wellenzahlbandmaximum eines Kristallisationsbandes mit einem differenz-polarisierten Infrarot-Spektrographen festgestellt. Beide, der Kristallanteil der Probe und die Orientierungsfunktion für die Übergangsmomente lassen sich aus den Resultaten unter Annahme einachsiger Orientierung auswerten. Letztere, die einachsige Orientierung, wurde mit Röntgenbeugung und Doppelbrechung sichergestellt.In den Experimenten mit kontinuierlicher Verlängerung zeigten die Orientierungsfunktionen der Kristallempfindlichen Banden bei 25% Verlängerung ein Maximum. Danach sanken sie rasch unter Wechsel ihres Vorzeichens von positiv nach negativ ab. Der Fließpunkt in der Spannungs-Dehnungs-Kurve und der Beginn des scharfen Abfalls der Kristallinität zeigen sich vom gleichen Verlängerungsgrad 25% ab.Diese Tatsachen werden aufgrund der Orientierung der kristallinen Phase erklärt, gefolgt von einem Abbau der Kristallite und einem Herausziehen der Molekülketten aus den Kristalliten. In den Spannungsrelaxationsversuchen wurden gewisse Änderungen der Orientierungsfunktionen für die verschiedenen charakteristischen Absorptionsbanden gefunden. Es ergaben sich geringe Differenzen in der Änderung der Orientierungsfunktionen für die amorphen und kristallempfindlichen Banden. Das steht im Gegensatz zu früheren Resultaten an vulkanisiertem Naturkautschuk. Bei letzteren war die Orientierung der Kristallphase beinahe unmittelbar nach der Dehnung vollständig, während in der amorphen Phase die molekularen Ketten nach und nach im Laufe der Spannungsrelaxation orientiert wurden.

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With 8 figures in 9 details and 1 table