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Properties of pteroylpolyglutamate hydrolase in pancreatic juice of the pig.

Authors :
Bhandari SD
Gregory JF 3rd
Renuart DR
Merritt AM
Source :
The Journal of nutrition [J Nutr] 1990 May; Vol. 120 (5), pp. 467-75.
Publication Year :
1990

Abstract

The function of pteroylpolyglutamate hydrolase (PPH) of pancreatic secretion in the hydrolysis of dietary polyglutamyl folates (PteGlun) in humans is unclear. In this study, PPH was detected in pancreatic juice collected from pigs during both fasting and postprandial conditions. The secretion of PPH was markedly increased following feeding. Pancreatic PPH showed the following characteristics: 1) endo/random hydrolysis of gamma-glutamyl peptide bonds of Pte-Glun substrates, yielding folic acid as the terminal product; 2) maximum activity at pH 4.0-4.5 and maximum stability at pH 7.0; 3) stimulation of activity by Zn2+ and 2-mercaptoethanol; 4) Km values for pteroyltriglutamate (PteGlu3) of 28.7 microM at pH 4.0 and 9.1 microM at pH 5.0; 5) apparent molecular weight of 29,000; and 6) isoelectric point within the range of 8.5-9.0. On the basis of PPH activity, volume of the postprandial secretion and pH profile of enzyme activity, it is suggested that pancreatic PPH may act in vivo in folate digestion and absorption to initiate the deconjugation of dietary PteGlun prior to the action of jejunal brush border PPH.

Details

Language :
English
ISSN :
0022-3166
Volume :
120
Issue :
5
Database :
MEDLINE
Journal :
The Journal of nutrition
Publication Type :
Academic Journal
Accession number :
2341911
Full Text :
https://doi.org/10.1093/jn/120.5.467