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Contents |
Alpha Lactalbumin
α-lactalbumin is a major protein in all kinds of milk studied so far. [1] α- lactalbumin contributes to cell lytic activity, cell growth inhibition, and apoptosis but most importantly, it interacts with UDP-galactosyltransferase [1] to form lactose synthetase via the following reaction:
UDP-galactose + glucose -+ lactose + UDP [2]
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| 1a4v, resolution 1.80Å () | |||||||||
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| Ligands: | |||||||||
| Activity: | Lactose synthase, with EC number 2.4.1.22 | ||||||||
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
Structure
α-lactalbumin is a small globular protein which is stabilized by four disulfide bonds with two structural domains. One domain is rich in α-helices, the other is rich in β-sheets and has a calcium binding site. [3]
: with alpha helices shown in pink rockets, and beta sheets shown in yellow planks.
: with nonpolar side chains in gray, polar side chains in purple, and associated water molecules in red.
: calcium ligands with amino acid contacts. water in pink, oxygen in red.
:cations in blue, anions in red, hydrophobic in gray, polar uncharged in light purple, backbone in dark purple.
Function
Recent Studies
Tryptophan is component of many alpha-lactalbumin proteins [4], the availability of which changes the ratio of plasma tryptophan to the sum of larger neutral amino acids (Trp-LNAA ratio). Tryptophan is a serotonin precursor and proper serotonin function in the brain has been shown to promote sleep regulation and cognitive processes. [5] Deficient serotonin function, possibly from chronic stress [4], can result in difficulty sleeping and therefore behavioral decline. Recent studies have shown that consumption of alpha-lactalbumin protein with enriched tryptophan content caused increased alertness and performance the morning after [5].
References
- ↑ 1.0 1.1 Vilotte JL. Alpha-lactalbumin: Gene Structure and Expression. <http://mammary.nih.gov/Reviews/gene_expression/Vilotte001/index.html>.
- ↑ Fitzgerald DK, Brodbeck URS, Kiyosawa I, Mawal R, Colvin B, Ebner KE. 1970. α-lactalbumin and the Lactose Synthetase Reaction. The Journal of Biological Chemistry. 245(8): 2103-2108.
- ↑ Hendrix TM, Griko Y, Privalov P. 1996. Energetics of structural domains in α-lactalbumin. Protein Science. 5923-5931.
- ↑ 4.0 4.1 Markus CR, Olivier B, de Haan EH. 2002. Whey protein rich in alpha-lactalbumin increases the ratio of plasma tryptophan to the sum of the other larger neutral amino acids and improves cognitive performance in stress vulnerable subjects. Am J Clin Nutr. 75(6):1051-1056.
- ↑ 5.0 5.1 Markus CR, Jonkman LM, Lammers JH, Deutz NE, Messer MH, Rigtering N. 2005. Evening intake of alpha-lactalbumin increases plasma tryptophan availability and improves morning alertness and brain measures of attention. Am J Clin Nutr. 81(5):1026-1033.
