Blood levels of the amino acid phenylalanine, as well as of the tryptophan breakdown product kynurenine, are found to be elevated in human immunodeficiency virus type 1 (HIV-1)-infected patients. Both essential amino acids, tryptophan and phenylalanine, are important precursor molecules for neurotransmitter biosynthesis. Thus, dysregulated amino acid metabolism may be related to disease-associa...

phenylketonuria (pku) is an inborn error of amino acid metabolism with an autosomal recessive inheritance caused in most cases by mutations in the phenylalanine hydroxylase (pah) gene. pku has wide allelic heterogeneity. here we report a novel heterozygous substitution (c.1223g>t (p.arg408leu)) in the pah gene in an iranian pku family. the patient was 19-yr-old female with diagnosis of moderate...

The intestinal peptide transporter PEPT1 mediates the uptake of di- and tripeptides derived from dietary protein breakdown into epithelial cells. Whereas the transporter appears to be essential to compensate for the reduced amino acid delivery in patients with mutations in amino acid transporter genes, such as in cystinuria or Hartnup disease, its physiological role in overall amino acid absorp...

Early studies of amino acid transport across the ovine placenta suggested that amino acids taken up by the placenta from the maternal circulation are delivered to the fetus with no major loss (placental amino acid utilization) or addition (placental amino acid production) (1). Recent data indicate that for some amino acids, this suggestion is not valid, and that amino acid metabolism is an impo...

The compartmentation of key processes in sugar, organic acid and amino acid metabolism was studied during the development of the flesh and seeds of grape (Vitis vinifera L.) berries. Antibodies specific for enzymes involved in sugar (cell wall and vacuolar invertases, pyrophosphate: fructose 6-phosphate phosphotransferase, aldolase, NADP-glyceraldehyde-P dehydrogenase, cytosolic fructose 1,6-bi...

Amino acid supplementation has been shown to enhance the liver-specific functions of cultured hepatocytes during plasma exposure. However, their transport through the cell membrane may restrict their availability for hepatic metabolism. Here, we focus on transport constraints related to uptake of the neutral amino acids and their impact on hepatic metabolism and liver-specific functions. Under ...

The scented gland is an organ responsible for producing musk in muskrats. During musk secretion season, the metabolism of glandular cells increases in the scented glands and a large amount of musk is synthesised. In this study, we collected scented gland arterial blood from six healthy adult male muskrats during non-secretion season (November). We also obtained scented gland arterial blood, ven...

The process of transamination takes place in many tissues in the body and is a fundamental mechanism in the metabolism of amino-acids. Basically it consists of the reversible transfer of an amino group from an amino-acid to a keto acid, providing a link between protein and carbohydrate metabolism. Although there appear to be a multitude of transamination systems, each catalysed by a specific en...