Free Amino Acids in Plasma and Urine by the Gasometric Ninhydrin-Carbon Dioxide Method

The carbon dioxide evolved when α-amino acids were heated for one hour at 85 °C. with ninhydrin was determined in a partially evacuated microdiffusion cell. Distillation of solvent from one chamber to the other was minimized by keeping the ionic concentrations of the reaction mixture and absorbing mixture approximately equal. The method was useful for samples of amino acids which liberated from 0.06 to 0.3 mgm. of carbon dioxide. The average deviation from the mean was somewhat less than 1% for samples liberating 0.2 mgm. of carbon dioxide. Use of the method for routine analysis of enzymatic digests resulted in substantial saving of time and material.

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Irradiation of mixed ices as a laboratory cometary model

Proceedings of the International Astronomical Union ◽

10.1017/s174392130802214x ◽

2008 ◽

Vol 4 (S251) ◽

pp. 447-448

Author(s):

Maria Colin-Garcia ◽

Alicia Negrón-Mendoza ◽

Sergio Ramos-Bernal ◽

Elizabeth Chacon

Keyword(s):

Carbon Dioxide ◽

Amino Acids ◽

Ionizing Radiation ◽

Carboxylic Acids ◽

Free Amino Acids ◽

Free Amino ◽

Organic Molecules ◽

Cometary Nuclei ◽

Icy Bodies

AbstractIcy bodies in space are being irradiated continuously by ionizing radiation. Therefore, the transformation of organic molecules trapped in extraterrestrial ices might have been possible. This work studied a bulk irradiation of a mixture of some constituents of cometary nuclei. The results show that the formation of different compounds, among them ammonia, carbon dioxide, amines, ureas, free amino acids, and oligomeric material, yields carboxylic acids, amino acids, and purines upon hydrolysis.

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THE METABOLISM OF VALERATE-3-C14 AND -5-C14 BY WHEAT STEM RUST UREDOSPORES

Canadian Journal of Biochemistry ◽

10.1139/o64-038 ◽

1964 ◽

Vol 42 (3) ◽

pp. 327-332 ◽

Cited By ~ 2

Author(s):

H. Reisener ◽

A. J. Finlayson ◽

W. B. McConnell

Keyword(s):

Carbon Dioxide ◽

Amino Acids ◽

Glutamic Acid ◽

Stem Rust ◽

Phosphate Buffer ◽

Free Amino Acids ◽

Free Amino ◽

Methyl Groups ◽

Wheat Stem Rust ◽

Carbon 14

Uredospores of wheat stem rust took up about 90% of the carbon-14 present either as valerate-3-C14 or as valerate-5-C14 in M/30 phosphate buffer pH 6.2 in 3 hours. The initial valerate concentration was 0.017 mM and spores were supplied at the rate of 250 mg/30 ml of buffer. Carbon 3 of the valerate was largely respired as carbon dioxide but carbon 5 was extensively incorporated into spore components. Free amino acids contained about 40% of the radioactivity in the spores labelled with valerate-5-C14 and glutamic acid was highly labelled. Carbon 1 contained 8.1% and carbon 5, 3.8% of the carbon-14 in this glutamic acid and thus internal carbons contained 88%. The results with valerate-3-C14 and with valerate-5-C14 compare well with those of experiments done earlier with propionate-1-C14 and propionate-3-C14 respectively. It is concluded that propionate is formed from carbons 3, 4, and 5 of valerate, and thus that carbon 3 is converted to carbon dioxide, and carbons 4 and 5 to the carboxyl and methyl groups respectively of acetate.

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