L-Threonine

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L-Threonine
2D structure for L-Threonine
Chemical Name	2-amino-3-hydroxy-butanoic acid
Chemical Formula	C₄H₉NO₃
CAS Number	72-19-5
Chemical Information	HMDB00167
Biochemical Taxonomy	Amino Acids
Functional Taxonomy	Not Available
Nutritional Taxonomy	Essential Amino Acids
Metabolic Pathways	Glycine, Serine and Threonine Metabolism
Biofluid Location	Blood Cerebrospinal Fluid (CSF) Saliva Urine
Tissue Location	All Tissues
Normal Biofluid Concentrations	Blood: 140.0 (107.0-173.0) uM Blood: 140.0 +/- 28.0 uM Blood: 146.0 +/- 22.0 uM Blood: 154.0 +/- 40.0 uM Blood: 215.0 +/- 60.0 uM Blood: 260.0 +/- 10.0 uM Cerebrospinal Fluid (CSF): 27.7 +/- 4.7 umol/mmol creatinine Cerebrospinal Fluid (CSF): 30 +/- 12 uM Cerebrospinal Fluid (CSF): 32.0 (4.00-60.0) uM Cerebrospinal Fluid (CSF): 34.7 +/- 6.2 uM Cerebrospinal Fluid (CSF): 37.4 +/- 7.6 uM Cerebrospinal Fluid (CSF): 45.9 +/- 12.3 uM Saliva: >10 uM Urine: 1.0 (0.16-2.4) umol/mmol creatinine Urine: 12.7 (4.934-20.4) umol/mmol creatinine Urine: 16.0 +/- 9.0 umol/mmol creatinine Urine: 18.0 +/- 9.6 umol/mmol creatinine Urine: 4.9 +/- 2.5 umol/mmol creatinine
Normal Tissue Concentrations	Not Available
Diseases / Conditions Related to Nutrition	Acute seizures Leukemia Leukemia with CNS disease Nondiabetic patients with Chronic Heart Failure Refractory localization-related epilepsy (RLE)
Other (Monogenic Disorders)	Not Available
Abnormal Biofluid Concentrations	Blood (Acute seizures): 114.0 (105.0-123.0) uM Blood (Nondiabetic patients with Chronic Heart Failure): 227.0 +/- 10.0 uM Blood (Refractory localization-related epilepsy (RLE)): 118.0 (114.0-122.0) uM Cerebrospinal Fluid (CSF) (Leukemia with CNS disease): 30.2 +/- 9.8 uM Cerebrospinal Fluid (CSF) (Leukemia): 41.0 +/- 15.9 uM
Abnormal Tissue Concentrations	Not Available
Physiological Processes	Not Available

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Introduction

guidelines
Threonine is an essential amino acid in humans. It is abundant in human plasma, particularly in newborns. Severe deficiency of threonine causes neurological dysfunction and lameness in experimental animals. Threonine is an immunostimulant which promotes the growth of thymus gland. It also can probably promote cell immune defense function. This amino acid has been useful in the treatment of genetic spasticity disorders and multiple sclerosis at a dose of 1 gram daily. It is highly concentrated in meat products, cottage cheese and wheat germ. (http://www.dcnutrition.com/AminoAcids/) The threonine content of most of the infant formulas currently on the market is approximately 20% higher than the threonine concentration in human milk. Due to this high threonine content the plasma threonine concentrations are up to twice as high in premature infants fed these formulas than in infants fed human milk. The whey proteins which are used for infant formulas are sweet whey proteins. Sweet whey results from cheese production. Threonine catabolism in mammals appears to be due primarily (70-80%) to the activity of threonine dehydrogenase (EC 1.1.1.103) that oxidizes threonine to 2-amino-3-oxobutyrate, which forms glycine and acetyl CoA, whereas threonine dehydratase (EC 4.2.1.16) that catabolizes threonine into 2-oxobutyrate and ammonia, is significantly less active. Increasing the threonine plasma concentrations leads to accumulation of threonine and glycine in the brain. Such accumulation affects the neurotransmitter balance which may have consequences for the brain development during early postnatal life. Thus, excessive threonine intake during infant feeding should be avoided. (PMID 9853925)

Biological Function

guidelines
Plasma threonine is uniquely resistant to the essential amino-acid-lowering effect of dietary protein deficiency. The finding that non-essential amino acids rise in plasma in response to dietary restriction reveals a stimulation of the flow of amino acids from non-critical tissue, mainly skeletal muscle. Threonine is spared from such a mobilization. This relationship of threonine to other essential amino acids (EAA) allows discriminating the origins of abnormal amino acid patterns in plasma. A pattern of low EAA levels with the exception of threonine indicates inadequate assimilation of dietary inadequacies. Such factors are generally catabolic since they are likely to involve increased cortisol and decreased anabolic factors such as insulin growth factor and testosterone. Since threonine is a potential source of glycine and serine, a pattern of concurrent low levels of these amino acids is a sign of impaired detoxification, tissue repair, and gluconeogenesis. From: laboratory evaluations in molcular medicine, nutrients, toxicants and cell regulators, 2005, J. Alexander Bralley and Richard S. Lord, ISBN 0-9673949-3-7