Urea utilization by rabbits fed a low-protein ration

Utilization of urea by adult rabbits fed straw, carrots, and sucrose was investigated. 1) In a 24-hr period following intravenous injection of 290 mg urea-N/kg body wt., part of the exogenous urea was excreted in urine and part was stored in body fluids; the remainder could not be accounted for and was presumed utilized in amino acid synthesis. An average of 212 ± 54 (sd) mg urea-N were utilized in eight such experiments (control urea-N excretion was 151 mg/day). Urea given per os over several days was also utilized. 2) When drinking water was removed, utilization of urea given per os, as reflected in nitrogen balance, increased; or, if no urea was given, nitrogen excretion decreased. 3) Antibacterial agents per os reduced exogenous urea utilization; or, if no urea was given, urea excretion increased, representing endogenous urea normally utilized (up to 40% of that formed in the body). 4) In acute experiments, blood urea moved into the saline-filled cecum at rates commensurate with the rates of utilization found in the other experiments. It was concluded that adult rabbits under these conditions can utilize urea at rates significant in nitrogen metabolism.

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Microbial amino acid synthesis and utilization in rats: the role of coprophagy

British Journal Of Nutrition ◽

10.1079/bjn19960077 ◽

1996 ◽

Vol 76 (5) ◽

pp. 701-709 ◽

Cited By ~ 28

Author(s):

David Torrallardona ◽

C. Ian Harris ◽

Malcolm F. Fuller

Keyword(s):

Body Weight ◽

Isotope Ratio Mass Spectrometry ◽

Acid Synthesis ◽

Exchange Chromatography ◽

The Body ◽

Amino Acid Synthesis ◽

Low Protein ◽

N Enrichment ◽

Fermentable Carbohydrates

Four rats were housed in cages with mesh floors; another four rats were housed in tubular anti-coprophagy cages, in which they could not turn round to reach their own faeces. Both groups were fed for 6 d on a low-protein diet containing fermentable carbohydrates and 15NH4Cl. At the end of the experiment the rats were killed and their carcasses were homogenized, lysine was isolated by ion-exchange chromatography and its 15N enrichment measured by isotope-ratio mass spectrometry. The 15N enrichment in the lysine of the microbial fraction of faeces and the total amount of lysine in the body were also determined in order to estimate the amount of microbial lysine absorbed. The 15N enrichment in body lysine of non-coprophagic rats was not different from that previously measured in rats given unlabelled NH4Cl, but in coprophagic rats it was significantly higher. The daily absorption of microbial lysine by the coprophagic rats accounted for 20·7 (SE 2·55) mg/kg body weight0·75 but was only 0·5 (SE 1·04) mg/kg body weight0·75 for the non-coprophagic rats. This value was not significantly different from zero. The utilization of microbial amino acids via coprophagy resulted in a higher weight gain (adjusted for intake) in the coprophagic group (15·5 g/6 d) than in the non-coprophagic rats (3·1 g/6 d). It was concluded that, in rats, the utilization of microbial lysine occurred exclusively via coprophagy.

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Growth inhibition of Neisseria gonorrhoeae isolates by L-phenylalanine and its analogues in defined media

Canadian Journal of Microbiology ◽

10.1139/m84-212 ◽

1984 ◽

Vol 30 (11) ◽

pp. 1319-1325 ◽

Cited By ~ 5

Author(s):

A. T. Hendry ◽

J. R. Dillon

Keyword(s):

Growth Rate ◽

Amino Acid ◽

Neisseria Gonorrhoeae ◽

Growth Inhibition ◽

Growth Rates ◽

Acid Synthesis ◽

The Other ◽

Amino Acid Synthesis ◽

Defined Media ◽

Agar Media

Growth inhibition by phenylalanine (0.25 mmol/L in defined agar media) was present in about 1% of over 1000 clinical isolates of Neisseria gonorrhoeae isolates tested. Turbidometry of several phenylalanine-sensitive isolates showed that their growth rates decreased in proportion to phenylalanine concentrations up to about 1 mmol/L. The growth rate was unaffected if 0.04 mmol/L tyrosine was also present. The phenylalanine analogue DL-3-fluorophenylalanine inhibited the growth of all 23 isolates further tested on agar. This inhibition was derepressed by phenylalanine in all 17 phenylalanine-resistant isolates. Phenylalanine plus tyrosine were required to derepress the analogue inhibition in the other six phenylalanine-sensitive isolates. Phenylalanine-sensitive isolates may have a defect in aromatic amino acid synthesis, not involving auxotrophy, but manifested through regulation of the pathways. Phenylalanine effectively repressed tyrosine and phenylalanine synthesis. In 125 isolates including 85 β-lactamase producers (PPNG) and 32 phenylalanine-sensitive isolates, phenylalanine inhibited 63.2% of 38 PPNG isolates carrying the 3.2 megadalton (Md) plasmid, but only one of 47 PPNG isolates carrying the 4.5 Md plasmid. PPNG isolates are most often of the proline, ornithine, or nonrequiring auxotypes. Phenylalanine sensitivity did not appear to be auxotype dependent.

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Supplementation with α-ketoglutarate to a low-protein diet enhances amino acid synthesis in tissues and improves protein metabolism in the skeletal muscle of growing pigs

Amino Acids ◽

10.1007/s00726-018-2618-3 ◽

2018 ◽

Vol 50 (11) ◽

pp. 1525-1537 ◽

Cited By ~ 13

Author(s):

Jiashun Chen ◽

Wenxuan Su ◽

Baoju Kang ◽

Qian Jiang ◽

Yurong Zhao ◽

...

Keyword(s):

Skeletal Muscle ◽

Amino Acid ◽

Protein Metabolism ◽

Acid Synthesis ◽

Growing Pigs ◽

Protein Diet ◽

Low Protein Diet ◽

Amino Acid Synthesis ◽

Low Protein

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Faculty Opinions recommendation of Photoredox activation of carbon dioxide for amino acid synthesis in continuous flow.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.727212076.793527478 ◽

2017 ◽

Author(s):

Donald Pinto ◽

Kumar Pabbisetty ◽

Vladimir Ladziata

Keyword(s):

Carbon Dioxide ◽

Amino Acid ◽

Continuous Flow ◽

Acid Synthesis ◽

Amino Acid Synthesis

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Petasis vs. Strecker Amino Acid Synthesis: Convergence, Divergence and Opportunities in Organic Synthesis

Molecules ◽

10.3390/molecules26061707 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1707

Author(s):

Wayiza Masamba

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Organic Synthesis ◽

Acid Synthesis ◽

Physical Sciences ◽

Amino Acid Synthesis

α-Amino acids find widespread applications in various areas of life and physical sciences. Their syntheses are carried out by a multitude of protocols, of which Petasis and Strecker reactions have emerged as the most straightforward and most widely used. Both reactions are three-component reactions using the same starting materials, except the nucleophilic species. The differences and similarities between these two important reactions are highlighted in this review.

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