Influence of Varying Dietary Protein Levels on Glycation of Albumin, Tryptophan and Valine in the Plasma of Chickens

Glycated Tryptophan PHP-THβC Incorporated into Various Chicken Embryonic Cells Constitutes Cellular Proteins

Glycation is a non-enzymatic reaction, and amino acids are glycated by glucose in vivo. Tryptophan is glycated with glucose to form two types of glycated compounds, tryptophan-Amadori product and (1R, 3S)-1-(D-gluco-1, 2, 3, 4, 5-pentahydroxypentyl)-1, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid (PHP-THβC). Although PHP-THβC can be incorporated into various chicken embryonic cells, the mechanism of its incorporation into intracellular fluids has not been clarified. In this study, we examined whether PHP-THβC once incorporated into various chicken embryonic cells can combine with proteins. Embryonic cells from the breast muscle, liver, spleen, kidney, proventriculus, gizzard, and skin were prepared and ³H-PHP-THβC was added to the culture medium at final concentrations of 0, 200, 400, 600, and 800 µM to examine the incorporation of PHP-THβC. After 18 h of incubation, radioactivity was measured in the whole-cell and protein fractions of the chicken embryonic cells. As PHP-THβC concentration increased from 0 to 600 µM, its accumulation in the whole-cell fractions of all types of chicken embryonic cells linearly increased and reached the maximum level. The saturated PHP-THβC accumulation in the whole-cell fractions suggests that PHP-THβC could be incorporated into intracellular fluids across cellular membranes by some transporter proteins. As PHP-THβC concentration increased from 0 to 800 µM, its accumulation in the protein fractions of all types of chicken embryonic cells increased in a linear manner and reached a maximum level in the 800 µM PHPTHβC treatment group. This is the first study to indicate that a part of PHP-THβC incorporated into the whole-cell fraction was detected in the protein fraction of various chicken embryonic cells.

Half-life of Fructosyl-valine in the Plasma of Chicks

Eighty 14-d-old single-comb White Leghorn male chicks were divided into 16 groups with five birds each. Fructosyl-valine, which is a valine-glucose-Amadori product, was intravenously (2,250 nmol/kg body weight) or orally (300 µmol/kg body weight) administered to chicks. Blood samples were collected 15, 30, 60, 120, 180, 360, 720 and 1440 min after administration. Plasma concentrations of fructosyl-valine were measured by using a liquid chromatography / mass spectrometry (LC/MS). The time course change in plasma fructosyl-valine concentration showed an exponential curve, as y=a+be-λt. The half-life of plasma fructosyl-valine was calculated by the following equation: (loge2)/λ. When fructosyl-valine was injected intravenously, the highest value for plasma fructosyl-valine concentration was observed 15 min after administration. When injected intravenously, the half-life of plasma fructosyl-valine was calculated to be 231 min. When fructosyl-valine was administered orally to chicks, the highest value for plasma fructosyl-valine concentration was observed 180 min after administration. When administered orally, the half-life of plasma fructosyl-valine was calculated to be 277 min. We conclude that the half-life of fructosyl-valine in plasma was approximately 4 h, which is longer than that of glycated tryptophan.