Lactase-phlorizin hydrolase

DAY A, CANADA F J, DIAZ J C, KROON P A, MCLAUCHLAN R, FAULDS C B, PLUMB G W, MORGAN M R A and WILLIAMSON G (2000) Dietary flavonoid and isoflavone glycosides are hydrolyzed by the lactase site of lactase phlorizin hydrolase. FEES Lett 468, 166-70. 

Potential enzymes involved in anthocyanin metabolism — The lactase phlorizin hydrolase (LPH EC 3.2.1.108) present only in the small intestine on the outside of the brush border membrane and the cytosolic P-glucosidase (CBG EC 3.2.1.1) found in many tissues, particularly in liver, can catalyze the deglycosylation (or hydrolysis) of polyphenols. LPH may play a major role in polyphenol metabolism... 

Day, A.J. et al.. Absorption of quercetin-3-glucoside and quercetin-4 -glucoside in the rat small intestine the role of lactase phlorizin hydrolase and the sodium-dependent glucose transporter, Biochem. Pharmacol., 65, 1199, 2003. 

Figure 2.3 Absorption, metabolism, and excretion of flavonoids. Glucuronidation, methyla-tion, and sulfation are catalyzed by UDP-glucuronyltransferase, catechol-O-methyltrasferase, and sulfotransferase, respectively. Abbreviation LPH, lactase phlorizin hydrolase.

Lactase-specific activity/lactase phlorizin hydrolase... 

Lactase (lactase phlorizin hydrolase [3.2.1.23]) has two activities [J-galactosidase activity, which catalyzes the hydrolysis of lactose, and a P-glucosidase activity, which is responsible for hydrolyzing phlorizin, a disaccharide found in some seaweeds and in the roots and bark of plants of the family Rosaceae. 

Jarvela I, Enattah NS, Kokkonen J, et al. Assignment of the locus for congenital lactase deficiency to 2q21,in the vicinity but separate from the lactase-phlorizin hydrolase gene. Am J Hum Genet 63 1078-1085,1998. 

Kuokkanen M, Enattah NS, OksanenA, et al. Transcriptional regulation of the lactase-phlorizin hydrolase gene by polymorphisms associated with adult-type hypolactasia. Gut 52 647-652,... 

Mantei, N., Villa, M., Enzler, T., Wacker, H., Boll, W., James, P, Hunziker, W., Semenza, G. (1988). Complete primary stmcture of human and rabbit lactase-phlorizin hydrolase implications for biosynthesis, membrane anchoring and evolution of the enzyme. EMBO J., 7, 2705-2713. 

Figure 2.1 Key step Luminal deglycosylation by LPH. For glycosylated flavonolds, this step determines whether the flavonold Is absorbed In the small Intestine. Degly-cosylatlon Is catalyzed by the brush border hydrolase, lactase phlorizin hydrolase. The alternative of transport by a sugar transporter followed by hydrolysis by cytosolic p-glucosidase Is a minor pathway for some flavonolds.

Lactase, which catalyzes the hydrolysis of lactose, is also a bifunctional enzyme. Lactase resides on the same polypeptide chain as phlorizin hydrolase. The entire protein is called lactase-phlorizin hydrolase. The N-lermu ial end of the polypeptide resides in the lumen, and bears the lactase activity. The central portion of the... 

Buller, H. A., Montgomery R, K Sasak, W. V and Grand, R. J. (1987). Biosynthesis, glyco-svlation, and intracellular transport of intestinal lactase-phlorizin hydrolase in rat. /. Biiji Cftcrrr. 262,17206-17211. 

Lactalbumin, 451 Lactase, 104,109-110 Lactase-phlorizin hydrolase, 109 Lactate dehydiosenase, 233,234-235 Lactation, see also Milk bone loss during. 777-778 energy lequirements, 301,306 Lacteal, 96 Lactose,... 

Keller, R, Semenza, G., and Shaltiel, S. (1995). Disposition of the carboxy-tail of rabbit lactase-phlorizin hydrolase elucidated with protein kinase A in vitro and in tissue culture. FEBS Lett. 368,563-567. 

Mitchelmore, C., Troelsen, J.T., Spodsberg, N., Sjostrom, H., Noren, O. 2000. Interaction between the homeodomain proteins Cdx2 and HNF1 alpha mediates expression of the lactase-phlorizin hydrolase gene. Biochem. J. 346, 529-535. 

On the other hand, the ready absorption of quercetin glucosides might be due to their hydrolyses either by the lactase phlorizin hydrolase or the cytosolic P-glycosidase in the enterocyte, although this explanation cannot be extended to all classes of flavonoids [11],... 

Figure 4 Enlargement of intestinal brush border, showing that polyphenol glycosides are not absorbed, transported into the enterocyte by a transporter, or hydrolyzed by a brush-border enzyme. Dotted arrows represent pathways followed by the polyphenols. PP-Glyc are polyphenol glycosides, PP-Conj are polyphenol conjugates, SGLTl is the sodium-dependent glucose transporter, and LPH is lactase phlorizin hydrolase.

Day AJ, Canada FJ, Diaz FC, Kroon PA, Mclauchlan R, Faulds C, Plumb GW, Morgan MRA, Williamson G. Role of lactase phlorizin hydrolase in the deglycosylation of dietary flavonol and isoflavone glycosides. FEES Lett 2000 478 71-75. 

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