Phytase activity in the small intestinal brush border membrane of the chicken

The kinetics, mineral dependency, and pH dependency of phytate hydrolysis by preparations of chicken small intestinal brush border membrane vesicles were determined. Substantial phytate hydrolysis occurred over the pH range from 5 to 6.5 with a maximum hydrolysis at pH of 6. Inclusion of 25 mM MgCl2...

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Bibliographic Details
Published in:Poultry science 1998-04, Vol.77 (4), p.557-563
Main Authors: Maenz, D.D. (University of Saskatchewan, Saskatoon, Saskatchewan, Canada), Classen, H.L
Format: Article
Language:English
Subjects:
6-Phytase - drug effects
6-Phytase - metabolism
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
Animals
BROILER CHICKENS
Chickens - metabolism
Chlorides - chemistry
Chlorides - pharmacology
CINC
Cohort Studies
CULTIVO DE TEJIDOS
CULTURE DE TISSU
CULTURE MEDIA
DUODENUM
ENZYMIC ACTIVITY
Female
FITASA
GALLINAS
HENS
Hydrogen-Ion Concentration
Hydrolysis
INTESTIN
Intestinal Mucosa - drug effects
Intestinal Mucosa - enzymology
Intestinal Mucosa - ultrastructure
INTESTINES
INTESTINOS
JEJUNUM
Kinetics
MAGNESIO
MAGNESIUM
Magnesium Chloride - chemistry
Magnesium Chloride - pharmacology
MEDIO DE CULTIVO
Microvilli - drug effects
Microvilli - enzymology
Microvilli - metabolism
MILIEU DE CULTURE
Minerals - chemistry
Minerals - pharmacology
Osmolar Concentration
PHYTASE
Phytic Acid - metabolism
POLLO DE ENGORDE
POULET DE CHAIR
POULETTE
SMALL INTESTINE
Time Factors
TISSUE CULTURE
ZINC
Zinc Compounds - chemistry
Zinc Compounds - pharmacology
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Summary:The kinetics, mineral dependency, and pH dependency of phytate hydrolysis by preparations of chicken small intestinal brush border membrane vesicles were determined. Substantial phytate hydrolysis occurred over the pH range from 5 to 6.5 with a maximum hydrolysis at pH of 6. Inclusion of 25 mM MgCl2 in the media doubled the rate of phytate hydrolysis. The brush border was shown to have no nonspecific acid phosphatase activity and excess phytate had no effect on alkaline phosphatase activity at pH 11. Under optimal conditions of pH 6 plus 25 mM MgCl2, a kinetic model of a single Michaelis-Menten type of enzymatic activity with a Km of 0.160 +/- 0.008 mM and a Vmax of 42.5 +/- 1.0 nmol/mg vesicle protein per min plus a small unsaturable component converged to the data (P 0.05). The specific and total activities of intestinal brush border phytase were highest in the duodenum (P 0.05) and decreased progressively down the length of the gut. Intestinal brush border vesicles prepared from broiler chicks and mature laying hens had comparable specific phytase activity. However, the total activity of brush border phytase was 35% higher in the small intestine of laying hens (P 0.05). Intestinal brush border phytase could contribute to phytate-phosphorus digestibility and may be subject to regulation in response to the dietary phosphorus and vitamin D status of the chicken
ISSN:0032-5791
1525-3171
DOI:10.1093/ps/77.4.557