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Literature summary for 2.4.1.22 extracted from
- Lactose synthetase (1975), Adv. Enzymol. Relat. Areas Mol. Biol., 43, 411-490.
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| 2,4,6-Trinitrobenzenesulfonate | modification of alpha-lactalbumin | Bos taurus |  |
| 2-Hydroxy-5-nitrobenzyl bromide | modification of alpha-lactalbumin | Bos taurus | |
| 2-mercaptoethanol | modification of alpha-lactalbumin | Bos taurus | |
| 2-Nitrophenylsulfenyl chloride | modification of alpha-lactalbumin | Bos taurus | |
| carbodiimide | at pH 4.5 rapid loss of the biological activity of alpha-lactalbumin | Bos taurus | |
| Dimethyl-(2-hydroxy-5-nitrobenzyl)-sulfonium bromide | modification of alpha-lactalbumin | Bos taurus | |
| 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 | |
| Formylkynurenine | - |
Bos taurus | |
| Formylkynurenine | - |
Cavia porcellus | |
| Formylkynurenine | - |
Homo sapiens | |
| Formylkynurenine | - |
Mammalia | |
| glycinamide | at pH 4.5 rapid loss of the biological activity of alpha-lactalbumin | Bos taurus | |
| Iodine | - |
Bos taurus | |
| 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 | |
| iodoacetate | - |
Cavia porcellus | |
| iodoacetate | - |
Homo sapiens | |
| iodoacetate | - |
Mammalia | |
| Maleic anhydride | - |
Bos taurus | |
| additional information | alpha-lactalbumin strongly inhibits the transfer of galactose to free N-acetylglucosamine | Mammalia | |
| N-Acetylimidazole | - |
Bos taurus | |
| N-Acetylimidazole | - |
Cavia porcellus | |
| N-Acetylimidazole | - |
Homo sapiens | |
| N-Acetylimidazole | - |
Mammalia | |
| Tetranitromethane | - |
Bos taurus | |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| additional information | - |
additional information | - |
Cavia porcellus | |
| additional information | - |
additional information | - |
Mammalia | |
| additional information | - |
additional information | - |
Homo sapiens | |
| additional information | - |
additional information | - |
Bos taurus |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| membrane | - |
Cavia porcellus | 16020 | - |
| membrane | - |
Homo sapiens | 16020 | - |
| membrane | - |
Bos taurus | 16020 | - |
| membrane | Golgi apparatus, galactosyl-transferase | Mammalia | 16020 | - |
| rough endoplasmic reticulum | alpha-lactalbumin in synthesized on the rough endoplasmic reticulum | Mammalia | 5791 | - |
| soluble | - |
Cavia porcellus | - |
- |
| soluble | - |
Homo sapiens | - |
- |
| soluble | - |
Bos taurus | - |
- |
| soluble | alpha-lactalbumin is a soluble milk protein secreted throughout lactation | Mammalia | - |
- |
Metals/Ions
| Metals/Ions | Comment | Organism | Structure |
|---|---|---|---|
| Ca2+ | 25% of the activation with Mn2+ | Mammalia | |
| Mg2+ | 25% of the activation with Mn2+ | Mammalia | |
| Mn2+ | - |
Cavia porcellus | |
| Mn2+ | - |
Homo sapiens | |
| Mn2+ | - |
Bos taurus | |
| Mn2+ | required, partially replaceable by Mg2+, Ca2+ | Mammalia | |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| UDPgalactose + glucose | Mammalia | biosynthesis of lactose | lactose + UDP | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Bos taurus | - |
- |
- |
| Capra hircus | - |
- |
- |
| Cavia porcellus | - |
- |
- |
| Homo sapiens | - |
- |
- |
| Mammalia | - |
female | - |
| Ovis aries | - |
- |
- |
| Sus scrofa | - |
- |
- |
Posttranslational Modification
| Posttranslational Modification | Comment | Organism |
|---|---|---|
| glycoprotein | - |
Cavia porcellus |
| glycoprotein | - |
Mammalia |
| glycoprotein | - |
Homo sapiens |
| 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
| Source Tissue | Comment | Organism | Textmining |
|---|---|---|---|
| mammary gland | - |
Cavia porcellus | - |
| mammary gland | - |
Mammalia | - |
| mammary gland | - |
Homo sapiens | - |
| mammary gland | - |
Bos taurus | - |
| milk | - |
Bos taurus | - |
| milk | - |
Ovis aries | - |
| milk | - |
Capra hircus | - |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| additional information | - |
- |
Homo sapiens |
| additional information | - |
assay | Mammalia |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| dUDPgalactose + D-glucose | - |
Mammalia | lactose + dUDP | - |
? | |
| dUDPgalactose + D-glucose | - |
Bos taurus | lactose + dUDP | - |
? | |
| UDPgalactose + alpha-methyl-D-glucose | - |
Mammalia | ? | - |
? | |
| UDPgalactose + D-glucose | - |
Cavia porcellus | lactose + UDP | - |
? | |
| UDPgalactose + D-glucose | - |
Mammalia | lactose + UDP | - |
? | |
| UDPgalactose + D-glucose | - |
Homo sapiens | lactose + UDP | - |
? | |
| UDPgalactose + D-glucose | - |
Sus scrofa | lactose + UDP | - |
? | |
| UDPgalactose + D-glucose | - |
Bos taurus | lactose + UDP | - |
? | |
| UDPgalactose + D-glucose | - |
Ovis aries | lactose + UDP | - |
? | |
| UDPgalactose + D-glucose | - |
Capra hircus | lactose + UDP | - |
? | |
| UDPgalactose + D-xylose | - |
Mammalia | ? | - |
? | |
| UDPgalactose + gentiobiose | - |
Mammalia | ? | - |
? | |
| UDPgalactose + glucose | biosynthesis of lactose | Mammalia | lactose + UDP | - |
? | |
| UDPgalactose + maltose | - |
Mammalia | ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| 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 |
| More | the three main polypeptides determined by SDS-PAGE of galactosyl transferase are active: 54000 Da, 48000 Da and 42000 Da | Bos taurus |
| More | MW of lactalbumin determined by nucleotide sequence MW of lactalbumin determined by nucleotide sequence: 14071 Da | Homo sapiens |
| More | MW of lactalbumin determined by nucleotide sequence MW of lactalbumin determined by nucleotide sequence: 14179 Da | Bos taurus |
| More | MW of lactalbumin determined by nucleotide sequence: guinea pig | Cavia porcellus |
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Release 2023.1 (January 2023)
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