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Literature summary extracted from

  • Hill, R.L.; Brew, K.
    Lactose synthetase (1975), Adv. Enzymol. Relat. Areas Mol. Biol., 43, 411-490.
    View publication on PubMed

Inhibitors

EC Number Inhibitors Comment Organism Structure
2.4.1.22 2,4,6-Trinitrobenzenesulfonate modification of alpha-lactalbumin Bos taurus
2.4.1.22 2-Hydroxy-5-nitrobenzyl bromide modification of alpha-lactalbumin Bos taurus
2.4.1.22 2-mercaptoethanol modification of alpha-lactalbumin Bos taurus
2.4.1.22 2-Nitrophenylsulfenyl chloride modification of alpha-lactalbumin Bos taurus
2.4.1.22 carbodiimide at pH 4.5 rapid loss of the biological activity of alpha-lactalbumin Bos taurus
2.4.1.22 Dimethyl-(2-hydroxy-5-nitrobenzyl)-sulfonium bromide modification of alpha-lactalbumin Bos taurus
2.4.1.22 dithiothreitol the rate of reduction of the disulfide bond in alpha-lactalbumin is much faster with dithiothreitol than mercaptoethanol, and at 24°C proceeds to completion within minutes at pH 8 Bos taurus
2.4.1.22 Formylkynurenine
-
 Bos taurus
2.4.1.22 Formylkynurenine
-
 Cavia porcellus
2.4.1.22 Formylkynurenine
-
 Homo sapiens
2.4.1.22 Formylkynurenine
-
 Mammalia
2.4.1.22 glycinamide at pH 4.5 rapid loss of the biological activity of alpha-lactalbumin Bos taurus
2.4.1.22 Iodine
-
 Bos taurus
2.4.1.22 iodoacetate modification of alpha-lactalbumin, carboxymethylation proceeds in the order His68, His32, His107. The activity decreases progressively as carboxymethylation proceeds, the fully carboxymethylated derivative has about 40% of the activity of the unmodified alpha-lactalbumin in lactose synthetase assay Bos taurus
2.4.1.22 iodoacetate
-
 Cavia porcellus
2.4.1.22 iodoacetate
-
 Homo sapiens
2.4.1.22 iodoacetate
-
 Mammalia
2.4.1.22 Maleic anhydride
-
 Bos taurus
2.4.1.22 additional information alpha-lactalbumin strongly inhibits the transfer of galactose to free N-acetylglucosamine Mammalia
2.4.1.22 N-Acetylimidazole
-
 Bos taurus
2.4.1.22 N-Acetylimidazole
-
 Cavia porcellus
2.4.1.22 N-Acetylimidazole
-
 Homo sapiens
2.4.1.22 N-Acetylimidazole
-
 Mammalia
2.4.1.22 Tetranitromethane
-
 Bos taurus

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
2.4.1.22 additional information
-
 additional information
-
 Cavia porcellus
2.4.1.22 additional information
-
 additional information
-
 Mammalia
2.4.1.22 additional information
-
 additional information
-
 Homo sapiens
2.4.1.22 additional information
-
 additional information
-
 Bos taurus

Localization

EC Number Localization Comment Organism GeneOntology No. Textmining
2.4.1.22 membrane
-
 Cavia porcellus 16020
-
2.4.1.22 membrane
-
 Homo sapiens 16020
-
2.4.1.22 membrane
-
 Bos taurus 16020
-
2.4.1.22 membrane Golgi apparatus, galactosyl-transferase Mammalia 16020
-
2.4.1.22 rough endoplasmic reticulum alpha-lactalbumin in synthesized on the rough endoplasmic reticulum Mammalia 5791
-
2.4.1.22 soluble
-
 Cavia porcellus
-
-
2.4.1.22 soluble
-
 Homo sapiens
-
-
2.4.1.22 soluble
-
 Bos taurus
-
-
2.4.1.22 soluble alpha-lactalbumin is a soluble milk protein secreted throughout lactation Mammalia
-
-

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
2.4.1.22 Ca2+ 25% of the activation with Mn2+ Mammalia
2.4.1.22 Mg2+ 25% of the activation with Mn2+ Mammalia
2.4.1.22 Mn2+
-
 Cavia porcellus
2.4.1.22 Mn2+
-
 Homo sapiens
2.4.1.22 Mn2+
-
 Bos taurus
2.4.1.22 Mn2+ required, partially replaceable by Mg2+, Ca2+ Mammalia

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
2.4.1.22 UDPgalactose + glucose Mammalia biosynthesis of lactose lactose + UDP
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
2.4.1.22 Bos taurus
-
-
-
2.4.1.22 Capra hircus
-
-
-
2.4.1.22 Cavia porcellus
-
-
-
2.4.1.22 Homo sapiens
-
-
-
2.4.1.22 Mammalia
-
 female
-
2.4.1.22 Ovis aries
-
-
-
2.4.1.22 Sus scrofa
-
-
-

Posttranslational Modification

EC Number Posttranslational Modification Comment Organism
2.4.1.22 glycoprotein
-
 Cavia porcellus
2.4.1.22 glycoprotein
-
 Mammalia
2.4.1.22 glycoprotein
-
 Homo sapiens
2.4.1.22 glycoprotein isolation of minor amounts of alpha-lactalbumin in milk which contains carbohydrate prosthetic group. Galactosyl transferase contains a considerable proportion of oligosaccharides Bos taurus

Source Tissue

EC Number Source Tissue Comment Organism Textmining
2.4.1.22 mammary gland
-
 Cavia porcellus
-
2.4.1.22 mammary gland
-
 Mammalia
-
2.4.1.22 mammary gland
-
 Homo sapiens
-
2.4.1.22 mammary gland
-
 Bos taurus
-
2.4.1.22 milk
-
 Bos taurus
-
2.4.1.22 milk
-
 Ovis aries
-
2.4.1.22 milk
-
 Capra hircus
-

Specific Activity [micromol/min/mg]

EC Number Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
2.4.1.22 additional information
-
-
 Homo sapiens
2.4.1.22 additional information
-
 assay Mammalia

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.4.1.22 dUDPgalactose + D-glucose
-
 Mammalia lactose + dUDP
-
 ?
2.4.1.22 dUDPgalactose + D-glucose
-
 Bos taurus lactose + dUDP
-
 ?
2.4.1.22 UDPgalactose + alpha-methyl-D-glucose
-
 Mammalia ?
-
 ?
2.4.1.22 UDPgalactose + D-glucose
-
 Cavia porcellus lactose + UDP
-
 ?
2.4.1.22 UDPgalactose + D-glucose
-
 Mammalia lactose + UDP
-
 ?
2.4.1.22 UDPgalactose + D-glucose
-
 Homo sapiens lactose + UDP
-
 ?
2.4.1.22 UDPgalactose + D-glucose
-
 Sus scrofa lactose + UDP
-
 ?
2.4.1.22 UDPgalactose + D-glucose
-
 Bos taurus lactose + UDP
-
 ?
2.4.1.22 UDPgalactose + D-glucose
-
 Ovis aries lactose + UDP
-
 ?
2.4.1.22 UDPgalactose + D-glucose
-
 Capra hircus lactose + UDP
-
 ?
2.4.1.22 UDPgalactose + D-xylose
-
 Mammalia ?
-
 ?
2.4.1.22 UDPgalactose + gentiobiose
-
 Mammalia ?
-
 ?
2.4.1.22 UDPgalactose + glucose biosynthesis of lactose Mammalia lactose + UDP
-
 ?
2.4.1.22 UDPgalactose + maltose
-
 Mammalia ?
-
 ?

Subunits

EC Number Subunits Comment Organism
2.4.1.22 More the enzyme is composed of two structurally and functionally dissimilar proteins: 1. UDP-galactose:N-acetylglucosamine-beta4-galactosyl transferase, EC 2.4.1.90. Its normal function is to catalyze the incorporation of galactose into 1,4-linkage with N-acetylglucosamine during the synthesis of oliogosaccharide prosthetic groups of certain glycoproteins, free N-acetylglucosamine also serves as an excellent acceptor for galactose leading to the formation of N-acetylgalactosamine, 2. alpha-lactalbumin, interaction of alpha-lactalbumin with the transferase leads to lactose synthesis when UDP-galactose and glucose are present Mammalia
2.4.1.22 More the three main polypeptides determined by SDS-PAGE of galactosyl transferase are active: 54000 Da, 48000 Da and 42000 Da Bos taurus
2.4.1.22 More MW of lactalbumin determined by nucleotide sequence MW of lactalbumin determined by nucleotide sequence: 14071 Da Homo sapiens
2.4.1.22 More MW of lactalbumin determined by nucleotide sequence MW of lactalbumin determined by nucleotide sequence: 14179 Da Bos taurus
2.4.1.22 More MW of lactalbumin determined by nucleotide sequence: guinea pig Cavia porcellus