Beta-Leucine

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Beta-Leucine
2D structure for Beta-Leucine
Chemical Name	(3S)-3-amino-4-methyl-pentanoic acid
Chemical Formula	C₆H₁₃NO₂
CAS Number	5699-54-7
Chemical Information	HMDB03640
Biochemical Taxonomy	Amino Acids
Functional Taxonomy	Not Available
Nutritional Taxonomy	Not Available
Metabolic Pathways	Not Available
Biofluid Location	Blood
Tissue Location	Not Available
Normal Biofluid Concentrations	Blood: 4.8 (2.0-8.0) umol/L
Normal Tissue Concentrations	Not Available
Diseases / Conditions Related to Nutrition	Patients with cobalamin deficiency
Other (Monogenic Disorders)	Not Available
Abnormal Biofluid Concentrations	Blood (Patients with cobalamin deficiency): 24.7 (10.0-50.0) umol/L
Abnormal Tissue Concentrations	Not Available
Physiological Processes	Not Available

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Introduction

guidelines
Beta-leucine is a metabolite that is in the middle of a controversy over its presence in the human body. While there are reports that claim it as a human metabolite, there are others that deny its existence. Two examples: Circulating levels of beta-leucine are elevated in the cobalamin-deficient state of pernicious anemia. Levels of leucine, on the other hand, are much lower. It is proposed that leucine 2,3-aminomutase, the cobalamin-dependent enzyme that catalyzes the interconversion of leucine and beta-leucine, is the affected enzyme in pernicious anemia and causes these results by preventing the synthesis of leucine from beta-leucine. The synthesis of leucine by human leukocytes and hair roots and by rat liver extracts has been shown to occur when either branched chain fatty acids or valine metabolites are the substances. The synthesis is dependent upon adenosylcobalamin and is inhibited by intrinsic factor. (PMID: 7430116) Using forms of beta-leucine and leucine that contain several deuterium atoms in place of several hydrogen atoms as internal standards, techniques have been developed which make it possible to detect and quantitate as little as 0.1 mumol/liter of beta-leucine or leucine in human serum and in incubations containing rat liver supernatant. beta-Leucine was not detectable, i.e. less than 0.1 mumol/liter, in any sera from 50 normal human subjects or in any sera from 50 cobalamin-deficient patients. Experiments in which beta-leucine, leucine, isostearic acid, or isocaproic acid were incubated with rat liver supernatant in the presence or absence of adenosylcobalamin or cobalamin-binding protein failed to demonstrate the formation of leucine or beta-leucine or their interconversion under any of the conditions studied. We conclude that beta-leucine is not present in human blood and that the existence of leucine 2,3-aminomutase in mammalian tissues remains to be established. (PMID 3356699)