QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wang, T. T. Y. Articles by Halsted, C. H. Search for Related Content PubMed PubMed Citation Articles by Wang, T. T. Y. Articles by Halsted, C. H.

Comparison of Folate Conjugase Activities in Human, Pig, Rat and Monkey Intestine¹

Division of Clinical Nutrition, Department of Internal Medicine, School of Medicine, University of California, Davis, CA 95616

Folate conjugase, an intestinal enzyme that hydrolyzes dietary polyglutamyl folate to the absorbable monoglutamyl derivative, is present in two locations in human jejunal mucosa: one on the brush border membrane, the other soluble and intracellar. Although the brush border enzyme has not been found in the rodent, a recent study demonstrated both brush border and intracellular folate conjugases in the pig with properties similar to the human enzymes. To confirm and expand these data, we compared folate conjugase activities in intestinal brush border and 30,000 x g supernatant fractions in human, pig, rat and monkey mucosa. In both the human and pig, brush border folate conjugase was active from pH 4.5 to 8.5, and activity was significantly increased by zinc acetate. In contrast, folate conjugase activity was negligible in rat and monkey mucosal brush borders. Intracellular folate conjugase was maximally active at pH 4.5 in the human, pig and monkey, whereas this enzyme was equally active from pH 4.0 to 7.5 in the rat. In each species, supernatant activity at pH 4.5 was completely inhibited by p-hydroxymercuribenzoate. Although folate conjugase was quantitatively more active in the human than in the pig intestine, the brush border and intracellular enzymes exhibited similar properties. Sucrase, lactase and aminopeptidase activities were also similar in the two species. Our data show marked species differences in mucosal folate conjugase activities and indicate that the pig may be a suitable experimental animal for further studies of folate hydrolysis and absorption in humans.

KEY WORDS: • folate conjugase • intestinal enzymes • folate absorption • pteroylpolyglutamate hydrolase

¹ This work was supported in part by grants from the National Institutes of Health, Nos. AM 18330 and T32 AM 07435.

Manuscript received 5 December 1984. Revision accepted 5 March 1985.

This article has been cited by other articles:

				T. B. Shafizadeh and C. H. Halsted {gamma}-Glutamyl Hydrolase, Not Glutamate Carboxypeptidase II, Hydrolyzes Dietary Folate in Rat Small Intestine J. Nutr., May 1, 2007; 137(5): 1149 - 1153. [Abstract] [Full Text] [PDF]

				L. M. Wallock-Montelius, J. A. Villanueva, R. E. Chapin, A.J. Conley, H. P. Nguyen, B. N. Ames, and C. H. Halsted Chronic Ethanol Perturbs Testicular Folate Metabolism and Dietary Folate Deficiency Reduces Sex Hormone Levels in the Yucatan Micropig Biol Reprod, March 1, 2007; 76(3): 455 - 465. [Abstract] [Full Text] [PDF]