Luis Federico Leloir was an Argentine physician and biochemist who received the 1970 Nobel Prize in Chemistry for his discovery of the metabolic pathways by which carbohydrates are synthesized and converted into energy in the body. Although born in France, Leloir received the majority of his education at the University of Buenos Aires and was director of the private research group Fundación Instituto Campomar until his death in 1987. His research into sugar nucleotides, carbohydrate metabolism, and renal hypertension garnered international attention and led to significant progress in understanding, diagnosing and treating the congenital disease galactosemia. Luis Leloir is buried in La Recoleta Cemetery, Buenos Aires.
Galactokinase is an enzyme (phosphotransferase) that facilitates the phosphorylation of α-D-galactose to galactose 1-phosphate at the expense of one molecule of ATP. Galactokinase catalyzes the second step of the Leloir pathway, a metabolic pathway found in most organisms for the catabolism of α-D-galactose to glucose 1-phosphate. First isolated from mammalian liver, galactokinase has been studied extensively in yeast, archaea, plants, and humans.
Galactosamine is a hexosamine derived from galactose with the molecular formula C6H13NO5. This amino sugar is a constituent of some glycoprotein hormones such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
UTP—glucose-1-phosphate uridylyltransferase also known as glucose-1-phosphate uridylyltransferase is an enzyme involved in carbohydrate metabolism. It synthesizes UDP-glucose from glucose-1-phosphate and UTP; i.e.,
Galactose epimerase deficiency, also known as GALE deficiency, Galactosemia III and UDP-galactose-4-epimerase deficiency, is a rare, autosomal recessive form of galactosemia associated with a deficiency of the enzyme galactose epimerase.
Uridine diphosphate galactose (UDP-galactose) is an intermediate in the production of polysaccharides. It is important in nucleotide sugars metabolism, and is the substrate for the transferase B4GALT5.
D-Galactose-1-phosphate is an intermediate in the intraconversion of glucose and uridine diphosphate galactose. It is formed from galactose by galactokinase.The improper metabolism of galactose-1-phosphate is a characteristic of galactosemia. The Leloir pathway is responsible for such metabolism of galactose and its intermediate, galactose-1-phosphate. Deficiency of enzymes found in this pathway can result in galactosemia; therefore, diagnosis of this genetic disorder occasionally involves measuring the concentration of these enzymes. One of such enzymes is galactose-1-phosphate uridylytransferase (GALT). The enzyme catalyzes the transfer of a UDP-activator group from UDP-glucose to galactose-1-phosphate. Although the cause of enzyme deficiency in the Leloir pathway is still disputed amongst researchers, some studies suggest that protein misfolding of GALT, which may lead to an unfavorable conformational change that impacts its thermal stability and substrate-binding affinity, may play a role in the deficiency of GALT in Type 1 galactosemia. Increase in galactitol concentration can be seen in patients with galactosemia; putting patients at higher risk for presenile cataract.
The enzyme UDP-glucose 4-epimerase, also known as UDP-galactose 4-epimerase or GALE, is a homodimeric epimerase found in bacterial, fungal, plant, and mammalian cells. This enzyme performs the final step in the Leloir pathway of galactose metabolism, catalyzing the reversible conversion of UDP-galactose to UDP-glucose. GALE tightly binds nicotinamide adenine dinucleotide (NAD+), a co-factor required for catalytic activity.
Nucleotide sugars are the activated forms of monosaccharides. Nucleotide sugars act as glycosyl donors in glycosylation reactions. Those reactions are catalyzed by a group of enzymes called glycosyltransferases.
In enzymology, a glutamine-fructose-6-phosphate transaminase (isomerizing) is an enzyme that catalyzes the chemical reaction
In enzymology, an alpha,alpha-trehalose-phosphate synthase (UDP-forming) is an enzyme that catalyzes the chemical reaction
In enzymology, a dolichyl-phosphate beta-glucosyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a lipopolysaccharide 3-alpha-galactosyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a starch synthase is an enzyme that catalyzes the chemical reaction
In enzymology, a sucrose synthase is an enzyme that catalyzes the chemical reaction
In enzymology, an UDP-glucose—hexose-1-phosphate uridylyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, an UTP—hexose-1-phosphate uridylyltransferase is an enzyme that catalyzes the chemical reaction
The gal operon is a prokaryotic operon, which encodes enzymes necessary for galactose metabolism. Repression of gene expression for this operon works via binding of repressor molecules to two operators. These repressors dimerize, creating a loop in the DNA. The loop as well as hindrance from the external operator prevent RNA polymerase from binding to the promoter, and thus prevent transcription. Additionally, since the metabolism of galactose in the cell is involved in both anabolic and catabolic pathways, a novel regulatory system using two promoters for differential repression has been identified and characterized within the context of the gal operon.
David Sidney Feingold was an American biochemist.
Ranwel Caputto was an Argentine biochemist. He was born in Buenos Aires, Argentina on January 1, 1914, and died on April 19, 1994. He is best known for winning the 1970 Nobel Prize in Chemistry under Dr. Luis Leloir.
