Related Experiment Video

Updated: Aug 16, 2026

One-step Metabolomics: Carbohydrates, Organic and Amino Acids Quantified in a Single Procedure
09:28

One-step Metabolomics: Carbohydrates, Organic and Amino Acids Quantified in a Single Procedure

Published on: June 25, 2010

Metabolism of threonine in newborn infants

Prabhu S Parimi1, Lourdes L Gruca, Satish C Kalhan

  • 1Schwartz Center for Metabolism & Nutrition, Bell Greve Bldg., Room G-735, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH 44109, USA. pparimi@metrohealth.org

American Journal of Physiology. Endocrinology and Metabolism
|July 21, 2005
PubMed

Insights

Newborn infants show higher threonine kinetics than adults. Threonine metabolism is linked to protein turnover, with oxidation increasing after feeding.

Area of Science:

  • Biochemistry
  • Human Physiology
  • Nutritional Science

Background:

  • Threonine is an essential amino acid crucial for protein synthesis and metabolism.
  • Understanding threonine kinetics in newborns is vital for assessing nutritional status and growth.
  • Limited data exists on threonine metabolism and its relationship to protein turnover in early infancy.

Purpose of the Study:

  • To quantify threonine kinetics, its oxidative pathway, and its relationship with whole-body protein turnover in healthy term infants within the first 48 hours of life.
  • To investigate the impact of fasting and formula feeding on threonine metabolism.
  • To elucidate the primary pathway for threonine degradation in neonates.

Main Methods:

  • Utilized stable isotope tracers ([U-(13)C(4),(15)N]threonine, [(2)H(5)]phenylalanine, and [(15)N]glycine) to measure threonine kinetics.
  • Quantified threonine oxidation by measuring expired carbon dioxide (CO(2)) and (13)C enrichment.
  • Assessed protein turnover by measuring the rate of appearance (R(a)) of threonine and phenylalanine.

Main Results:

  • Threonine R(a) was significantly higher in newborns compared to adults (136 +/- 37 micromol.kg(-1).h(-1)).
  • Formula feeding decreased threonine R(a) (P < 0.05), while increasing threonine oxidation (20% fasting vs. 26% fed, P < 0.05).
  • A strong positive correlation existed between threonine and phenylalanine R(a) (r(2) = 0.65), suggesting linked protein turnover.

Conclusions:

  • Newborns exhibit a higher threonine flux relative to phenylalanine, indicating increased turnover of threonine-enriched proteins.
  • Threonine is primarily degraded via the glycine-independent serine/threonine dehydratase pathway.
  • These findings provide critical insights into neonatal amino acid metabolism and nutritional requirements.

More Related Videos

Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids07:26

Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids

Published on: January 26, 2012

Liquid Chromatography Coupled to Refractive Index or Mass Spectrometric Detection for Metabolite Profiling in Lysate-based Cell-free Systems14:42

Liquid Chromatography Coupled to Refractive Index or Mass Spectrometric Detection for Metabolite Profiling in Lysate-based Cell-free Systems

Published on: September 23, 2021

Related Concept Videos

Pharmacokinetics in Pediatric Patients: Drug Metabolism01:24

Pharmacokinetics in Pediatric Patients: Drug Metabolism

In pediatric care, understanding the nuances of hepatic drug metabolism is crucial, as it significantly differs from that of adults. This divergence is primarily due to the developmental stage of drug-metabolizing enzymes, which affects how medications are processed in the body. In neonates, for instance, the activity of Phase I enzymes—critical for the initial breakdown of drugs—is markedly reduced, functioning at just 20–40% of the levels seen in adults. This reduction poses a challenge in...
Inborn Errors of Metabolism01:20

Inborn Errors of Metabolism

Phenylketonuria (PKU) is a protein metabolism disorder characterized by high blood levels of the amino acid phenylalanine. This results from a mutation in the gene responsible for phenylalanine hydroxylase, an enzyme that converts phenylalanine into tyrosine. When this enzyme is deficient, phenylalanine builds up in the blood, leading to symptoms such as vomiting, rashes, seizures, growth deficiency, and severe mental retardation. An early diagnosis and a diet restricting phenylalanine intake...
Overview of Protein Metabolism01:21

Overview of Protein Metabolism

Proteins are broken down into amino acids during digestion. Unlike fats and carbohydrates, which are stored for later use, proteins are not. Instead, amino acids are either used to produce ATP through oxidation or contribute to the creation of new proteins for the growth and repair of the body. Any surplus amino acids from the diet are converted into glucose or triglycerides rather than excreted.
Amino acids play various roles in the body once they are absorbed into cells. They are restructured...
Amino Acid Biosynthetic Pathways01:29

Amino Acid Biosynthetic Pathways

Amino acid biosynthesis is essential for cell growth, protein synthesis, and metabolic regulation. Cells generate essential and non-essential amino acids from metabolic intermediates to sustain vital biological functions. These intermediates originate from key metabolic pathways: glycolysis, the tricarboxylic acid (TCA) cycle, and the pentose phosphate pathway. Important precursors include α-ketoglutarate, pyruvate, oxaloacetate, phosphoenolpyruvate, and erythrose-4-phosphate, which provide...
Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase01:27

Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase

Phase II biotransformation reactions are essential for detoxifying and eliminating xenobiotics, including many pharmaceutical compounds. These reactions typically involve conjugation, the covalent attachment of polar endogenous groups such as glucuronic acid, sulfate, methyl, or acetyl moieties to functional groups introduced during Phase I metabolism. The resulting conjugates are more water-soluble, enabling efficient renal or biliary excretion.The major classes of Phase II enzymes include...
Pharmacokinetics in Pediatric Patients: Drug Excretion01:26

Pharmacokinetics in Pediatric Patients: Drug Excretion

In pediatric medicine, understanding the renal function and drug elimination nuances is crucial for administering safe and effective treatments. Newborns, in particular, display markedly slower renal functions than adults, profoundly affecting how drugs are cleared from their bodies. This slower drug clearance requires clinicians to extend the dosing intervals for many medications to prevent drug accumulation and toxicity while ensuring therapeutic efficacy.One key area where these adjustments...