Browsing by Author "Ishida, Kenneth P."

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Comparison of reduction methods for gas chromatography/mass spectrometry identification and quantitation of uronic acids in acidic polysaccharides
(1989-06) Quintero, Ernesto J.; Ishida, Kenneth P.; Gordon, Grisel; Geesey, Gill G.
Four different reduction procedures were evaluated for their efficiency in dideuterating uronic acids in acidic polysaccharides. A method using 8 M urea to dissolve the polymers and 1-chyclohexyl-3-(2-morpholinoethyl)-carbodiimide metho-p-toluene sulfonate (CMC) to form uronide esters provided the best uronide dideuteration and uronic acid and neutral hexose sugar recoveries. Of the total uronic acid detected by a colorimetric assay, 20–30% was recovered as specific uronic acids from low-viscosity biopolymers by gas chromatography—mass spectrometry when this reduction procedure was employed. Lower and more variable recoveries of uronic acids were obtained from high-viscosity polysaccharides. The technique provided positive identification of the uronic acids in all five acidic polymers tested, even when the polymer also contained the corresponding neutral sugar analogue. Although quantitative recovery of uronic acids was not obtained, the technique nevertheless provides useful information on the relative contribution of uronic acids and neutral sugars in unpurified low-viscosity polymer preparations.
Comparison of the amide i/ii intensity ratio of solution and solid-state proteins samples by transmission, attenuated total reflectance, and diffuse reflectance spectrometry
(1993-05) Ishida, Kenneth P.; Griffiths, Peter R.
The absolute and relative differences in amide I and amide II band intensities of albumin, β-lactoglobulin, and myoglobin as measured by attenuated total reflection infrared (ATR-IR) spectrometry, transmission of aqueous solutions, and KBr disks and diffuse reflectance (DR) spectrometry are compared. The amide I/II intensity ratios of the proteins sampled by ATR, DR, and transmission spectrometry of KBr disks were similar and were significantly different from the intensity ratios of the proteins in solution. The absolute amide II band intensity of dissolved proteins did not vary significantly with changes in pH. The difference in amide I/II intensity ratios between solution and adsorbed proteins was attributed to differences in secondary and possible tertiary structure. The thickness of each protein film was estimated with the use of the absorptivities calculated from the amide II band intensities of the KBr disk spectra. pH had a significant influence on the thickness of the adsorbed films. Differences in film thickness were attributed to a difference in the orientation of the protein molecules at the surface of the germanium internal reflection element.