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Mammalian isovalthine metabolism
K J Rutherfurd-Markwick1, Q R Rogers, W H Hendriks
1Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand. K.J.Rutherfurd@massey.ac.nz
Journal of Animal Physiology and Animal Nutrition
|December 31, 2008
Summary
Isovalthine, a sulfur amino acid, is found in normal cat urine. Its carbon skeleton origin is unknown, despite research into its biosynthesis and potential links to hypercholesterolemia.
Area of Science:
- Biochemistry
- Metabolic Research
- Amino Acid Metabolism
Background:
- Isovalthine is a branched-chain sulfur amino acid identified in the urine of healthy adult cats.
- Urinary isovalthine concentrations in cats range from 24-66 micromol/l and are gender-independent.
- Isovalthinuria can be experimentally induced in various species, including humans, rats, and dogs.
Purpose of the Study:
- To review and discuss existing experimental data on isovalthine metabolism.
- To explore the biosynthesis of isovalthine, particularly the origin of its carbon skeleton.
- To investigate the potential association between isovalthine and hypercholesterolemia.
Main Methods:
- Review of historical experimental data from the 1960s concerning isovalthine induction and biosynthesis.
- Analysis of studies investigating the sulfur and carbon origins of isovalthine.
- Examination of evidence questioning the presence of isovalthine in hypercholesterolemia patients.
Main Results:
- The origin of the sulfur atom in isovalthine has been identified as cysteine or methionine.
- The origin of the carbon skeleton of isovalthine remains undetermined.
- Administration of Bromural (alpha-bromoisovalerylurea) to humans can lead to isovalthine formation post-hydrolysis, casting doubt on earlier findings.
Conclusions:
- While the sulfur source for isovalthine is known, its carbon skeleton's origin requires further elucidation.
- The link between isovalthine and hypercholesterolemia is questionable due to drug-induced formation.
- Further research is needed to fully understand isovalthine metabolism and its physiological significance.
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