Methionine Metabolism in Piglets Fed dl-Methionine or Its Hydroxy Analogue Was Affected by Distribution of Enzymes Oxidizing These Sources to Keto-Methionine

Previous evidence shows that the extensive catabolism of dietary essential amino acids (AA) by the intestine results in decreased availability of these AA for protein synthesis in extraintestinal tissues. This raises the possibility that extraintestinal availability of AA may be improved by supplyin...

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Published in:Journal of agricultural and food chemistry 2010-02, Vol.58 (3), p.2008-2014
Main Authors: Fang, Zhengfeng, Luo, Hefeng, Wei, Hongkui, Huang, Feiruo, Qi, Zhili, Jiang, Siwen, Peng, Jian
Format: Article
Language:English
Subjects:
Alcohol Oxidoreductases - genetics
Alcohol Oxidoreductases - metabolism
Amidohydrolases - genetics
Amidohydrolases - metabolism
amino acid metabolism
Animal Feed - analysis
Animal Nutritional Physiological Phenomena
Animals
Biological and medical sciences
dl-methionine
dl-methionine hydroxy analogue
enzyme activity
enzymes
experimental diets
Female
Food industries
Fundamental and applied biological sciences. Psychology
Intestines - enzymology
Intestines - metabolism
keto-methionine
Male
methionine
Methionine - analogs & derivatives
Methionine - metabolism
Molecular Nutrition
nutritive value
oxidation
Oxidation-Reduction
parenteral feeding
piglet feeding
piglets
Stomach - enzymology
Stomach - metabolism
Swine - metabolism
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Summary:Previous evidence shows that the extensive catabolism of dietary essential amino acids (AA) by the intestine results in decreased availability of these AA for protein synthesis in extraintestinal tissues. This raises the possibility that extraintestinal availability of AA may be improved by supplying the animal with an AA source more of which can bypass the intestine. To test this hypothesis, six barrows (35-day-old, 8.6 ± 1.4 kg), implanted with arterial, portal, and mesenteric catheters, were fed a dl-methionine (dl-MET) or dl-2-hydroxy-4-methylthiobutyrate (dl-HMTB) diet once hourly and infused intramesenterically with 1% p-amino hippurate. Although the directly available l-MET in dl-MET diet was about 1.2-fold that in dl-HMTB diet, the net portal appearance of l-MET was not different between the two diets. Compared with the low mRNA abundance and low activity of d-2-hydroxy acid dehydrogenase (d-HADH) and l-2-hydroxy acid oxidase (l-HAOX) in the intestine, the high mRNA abundance and high activity of d-AA oxidase (d-AAOX) indicated that the intestine had a relatively higher capacity of d-MET utilization than of dl-HMTB utilization to l-MET synthesis and its subsequent metabolism. However, in contrast to the much lower d-AAOX activity (nmol/g tissue) in the stomach than in the liver and kidney, both d-HADH and l-HAOX activity in the stomach was comparable with those in the liver and/or kidney, indicating the substantial capacity of the stomach to convert dl-HMTB to l-MET. Collectively, the difference in distribution of activity and mRNA abundance of d-AAOX, d-HADH, and l-HAOX in the piglets may offer a biological basis for the similar portal appearance of l-MET between dl-MET and dl-HMTB diets, and thus may provide new important insights into nutritional efficiency of different l-MET sources.
ISSN:0021-8561
1520-5118
DOI:10.1021/jf903317x