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On the role of solvent in complexation equilibiria. II. The acid-base chemistry of some sulfhydryl and ammonium-containing amino acids in water—acetonitrile mixed solvents (1979)

Pillai, Lakshmikumar ; Boss, Roger D. ; Greenberg, Mark S.

Springer

Journal of solution chemistry 8 (1979), S. 635-646

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ISSN: 1572-8927

Keywords: Amino acids ; cysteine ; penicillamine ; glutathione ; microscopic ionization ; mixed solvents ; water-acetonitrile ; potentiometry ; ultraviolet spectroscopy ; acid-base chemistry

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract The macroscopic and microscopic acid-base chemistry of a series of sulfhydryl and ammonium-containing amino acids HS−R−NH3 [R=−CH2CH(COOH)−, cysteine (CYS); R=−C(CH3)2CH(COOH)−, penicillamine (PEN); R=−CH(COOH)CH2CH2CONHCH(−CH2)CONHCH2COOH, glutathione (GSH)] was characterized in water and its binary mixtures with acetonitrile (16.3, 34.2, and 53.9 mass % acetonitrile). Macroscopic acid dissociation constants were obtained by potentiometric titration using the glass-calomel electrode pair. Microscopic acid dissociation constants were calculated from ultraviolet absorption measurements at ca. 232 nm where the deprotonated sulfhydryl group absorbs. The macroscopic constants decrease uniformly as the solvent becomes enriched in acetonitrile. The microscopic constants, which characterize the relative concentrations of the two monoprotonated tautomers of the molecules (I and II) reveal that as the solvent becomes enriched in acetonitrile, the fraction of molecules existing as highly charged tautomer I decreases for CYS (0.68–0.40), PEN (0.85–0.34), and GSH (0.61–0.30). These results are related to the decreasing concentration of water as the solvent becomes enriched in acetonitrile.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01033694

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Alpha-fetoprotein and liver cell proliferation in rats fed choline-deficient diet (1976)

Boss, J. H. ; Rosenmann, E. ; Zajicek, G.

Springer

European journal of nutrition 15 (1976), S. 211-216

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ISSN: 1436-6215

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine

Description / Table of Contents: Zusammenfassung Der3H-Thymidin-Aufnahmeindex in der Leber und das Serum AFP wurden bei Ratten, welche bei einer standardisierten Laboratoriumsdiät oder mit einer Cholinmangeldiät ernährt wurden, bestimmt. Es wurde festgestellt, daß die Proliferation der Leberzellen bei Tieren, die die Mangeldiät erhalten haben, signifikant erhöht war. Weiterhin wurde bei einigen dieser Ratten eine erhöhte Serumkonzentration des AFP gefunden. Die Befunde deuten darauf hin, daß die vermehrte Synthese des AFP einer Leberzellregeneration, welche sekundär zu einem Leberschaden entsteht, entspricht.

Notes: Summary Liver3H-thymidine labelling index and serum AFP were determined in rats fed a standard laboratory or choline deficient diet. A significant increase in the rate of liver cell proliferation was evidenced in animals on the deficient diet. Furthermore, elevated serum AFP levels were detected in a proportion of these rats. It is suggested that increased synthesis of AFP corresponds to liver cell regeneration secondary to hepatic damage.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02018443

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