scholarly journals Impacts of dietary calcium, phytate, and phytase on inositol hexakisphosphate degradation and inositol phosphate release in different segments of digestive tract of broilers

2017 ◽  
Vol 96 (10) ◽  
pp. 3626-3637 ◽  
Author(s):  
W. Li ◽  
R. Angel ◽  
S.-W. Kim ◽  
K. Brady ◽  
S. Yu ◽  
...  
Keyword(s):  
Digestive Tract ◽  
Inositol Phosphate ◽  
Dietary Calcium ◽  
Inositol Hexakisphosphate ◽  
Phosphate Release

scholarly journals Inositol phosphate release and steroidogenesis in rat adrenal glomerulosa cells. Comparison of the effects of endothelin, angiotensin II and vasopressin

1990 ◽  
Vol 271 (3) ◽  
pp. 791-796 ◽  
Author(s):  
E A Woodcock ◽  
P J Little ◽  
J K Tanner
Keyword(s):  
Angiotensin Ii ◽  
Metabolic Pathways ◽  
Inositol Phosphate ◽  
The Other ◽  
Relative Importance ◽  
Phosphate Release ◽  
Phosphatidylinositol Turnover ◽  
Transient Rise ◽  
Glomerulosa Cells ◽  
Stimulation Of

Endothelin has steroidogenic activity in adrenal glomerulosa cells, as do two other vasoconstrictor peptides, angiotensin II and vasopressin. The steroidogenic activities of angiotensin II and vasopressin are probably mediated via the phosphatidylinositol-turnover pathway and associated changes in cytosolic Ca2+ concentration. Endothelin caused a steroidogenic response, which was small compared with that to angiotensin II and quantitatively similar to the vasopressin response. Cytosolic free Ca2+ responses were similarly higher to angiotensin II than to either of the other two peptides. However, total inositol phosphate responses to endothelin and angiotensin II were similar when these were measured over 20 min, and were quantitatively greater than the vasopressin response. A detailed study has been made of the phosphatidylinositol-turnover response to endothelin in comparison with responses to angiotensin II and vasopressin. Each of the three peptides produced a rapid and transient rise in Ins(1,4,5)P3 (max. 5-15 s), followed by a slow sustained rise. Ins(1,4,5)P3 was metabolized by both dephosphorylation and phosphorylation pathways, but the relative importance of the two metabolic pathways was different under stimulation by each of the three peptides. These findings show that adrenal glomerulosa cells can distinguish between the stimulation of phosphatidylinositol turnover by three different effectors. These differences in the pathway may be associated with the observed different steroidogenic and Ca2+ responses to the three peptides.

The pathway of dephosphorylation of myo-inositol hexakisphosphate by phytate-degrading enzymes of different Bacillus spp.

2002 ◽  
Vol 48 (11) ◽  
pp. 986-994 ◽  
Author(s):  
Ralf Greiner ◽  
Adelazim Farouk ◽  
Marie Larsson Alminger ◽  
Nils-Gunnar Carlsson
Keyword(s):  
Bacillus Amyloliquefaciens ◽  
High Performance ◽  
Inositol Phosphate ◽  
Kinetic Studies ◽  
Enzyme Concentration ◽  
Inositol Hexakisphosphate ◽  
Prolonged Incubation ◽  
Chromatography Analysis ◽  
Degrading Enzymes ◽  
Bacillus Spp

The pathway of dephosphorylation of myo-inositol hexakisphosphate by the phytate-degrading enzymes of Bacillus subtilis 168, Bacillus amyloliquefaciens ATCC 15841, and Bacillus amyloliquefaciens 45 was established using a combination of high-performance ion chromatography analysis and kinetic studies. The data demonstrate that all the Bacillus phytate-degrading enzymes under investigation dephosphorylate myo-inositol hexakisphosphate by sequential removal of phosphate groups via two independent routes; the routes proceed via D-Ins(1,2,4,5,6)P5 to Ins(2,4,5,6)P4 to finally Ins(2,4,6)P3 or D-Ins(2,5,6)P3 and via D-Ins(1,2,4,5,6)P5 to D-Ins(1,2,5,6)P4 to finally D-Ins(1,2,6)P3. The resulting myo-inositol trisphosphate D-Ins(1,2,6)P3 was degraded via D-Ins(2,6)P2 to finally Ins(2)P after prolonged incubation times in combination with increased enzyme concentration. Key words: Bacillus spp., myo-inositol phosphate isomers, phytase, phytate degradation.

myo-Inositol phosphate isomers generated by the action of a phytate-degrading enzyme from Klebsiella terrigena on phytate

2006 ◽  
Vol 52 (8) ◽  
pp. 759-768 ◽  
Author(s):  
Ralf Greiner ◽  
Nils-Gunnar Carlsson
Keyword(s):  
Inositol Phosphate ◽  
Minor Importance ◽  
Microbial Pathogenesis ◽  
Inositol Hexakisphosphate ◽  
Degrading Enzyme ◽  
Dual Pathway ◽  
Second Dual ◽  
Phytate Hydrolysis ◽  
First Time

For the first time a dual pathway for dephosphorylation of myo-inositol hexakisphosphate by a histidine acid phytase was established. The phytate-degrading enzyme of Klebsiella terrigena degrades myo-inositol hexakisphosphate by stepwise dephosphorylation, preferably via D-Ins(1,2,4,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, D-Ins(1,2)P2 and alternatively via D-Ins(1,2,4,5,6)P5, Ins(2,4,5,6)P4, D-Ins(2,4,5)P3, D-Ins(2,4)P2 to finally Ins(2)P. It was estimated that more than 98% of phytate hydrolysis occurs via D-Ins(1,2,4,5,6)P5. Therefore, the phytate-degrading enzyme from K. terrigena has to be considered a 3-phytase (EC 3.1.3.8). A second dual pathway of minor importance could be proposed that is in accordance with the results obtained by analysis of the dephosphorylation products formed by the action of the phytate-degrading enzyme of K. terrigena on myo-inositol hexakisphosphate. It proceeds preferably via D-Ins(1,2,3,5,6)P5, D-Ins(1,2,3,6)P4, Ins(1,2,3)P3, D-Ins(2,3)P2 and alternatively via D-Ins(1,2,3,5,6)P5, D-Ins(2,3,5,6)P4, D-Ins(2,3,5)P3, D-Ins(2,3)P2 to finally Ins(2)P. D-Ins(2,3,5,6)P4, D-Ins(2,3,5)P3, and D-Ins(2,4)P2 were reported for the first time as intermediates of enzymatic phytate dephosphorylation. A role of the phytate-degrading enzyme from K. terrigena in phytate breakdown could not be ruled out. Because of its cytoplasmatic localization and the suggestions for substrate recognition, D-Ins(1,3,4,5,6)P5 might be the natural substrate of this enzyme and, therefore, may play a role in microbial pathogenesis or cellular myo-inositol phosphate metabolism.Key words: myo-inositol phosphate isomers, phytate-degrading enzyme, phytate, phytase, Klebsiella terrigena.

Synthesis of inositol phosphate ligands of plant hormone–receptor complexes: pathways of inositol hexakisphosphate turnover

2012 ◽  
Vol 444 (3) ◽  
pp. 601-609 ◽  
Author(s):  
David E. Hanke ◽  
Paroo N. Parmar ◽  
Samuel E. K. Caddick ◽  
Porntip Green ◽  
Charles A. Brearley
Keyword(s):  
Hormone Receptor ◽  
Plant Hormone ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Leaf Tissue ◽  
Phosphate Metabolism ◽  
Inositol Hexakisphosphate ◽  
Receptor Complexes ◽  
Inositol Phosphate Metabolism ◽  
Phosphate Ligands

Reduction of phytate is a major goal of plant breeding programs to improve the nutritional quality of crops. Remarkably, except for the storage organs of crops such as barley, maize and soybean, we know little of the stereoisomeric composition of inositol phosphates in plant tissues. To investigate the metabolic origins of higher inositol phosphates in photosynthetic tissues, we have radiolabelled leaf tissue of Solanum tuberosum with myo-[2-3H]inositol, undertaken a detailed analysis of inositol phosphate stereoisomerism and permeabilized mesophyll protoplasts in media containing inositol phosphates. We describe the inositol phosphate composition of leaf tissue and identify pathways of inositol phosphate metabolism that we reveal to be common to other kingdoms. Our results identify the metabolic origins of a number of higher inositol phosphates including ones that are precursors of cofactors, or cofactors of plant hormone–receptor complexes. The present study affords alternative explanations of the effects of disruption of inositol phosphate metabolism reported in other species, and identifies different inositol phosphates from that described in photosynthetic tissue of the monocot Spirodela polyrhiza. We define the pathways of inositol hexakisphosphate turnover and shed light on the occurrence of a number of inositol phosphates identified in animals, for which metabolic origins have not been defined.

scholarly journals Effect of catecholamines on Na/H exchange in vascular smooth muscle cells.

1986 ◽  
Vol 103 (5) ◽  
pp. 2053-2060 ◽  
Author(s):  
N E Owen
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Adrenergic Receptor ◽  
Inositol Phosphate ◽  
Major Pathway ◽  
Phosphate Release ◽  
Potency Order ◽  
Stimulation Of

Catecholamines were found to activate Na/H exchange in a concentration-dependent manner in primary cultures of vascular smooth muscle cells (VSMC). The potency order was found to be epinephrine greater than norepinephrine greater than isoproterenol. The major pathway for catecholamine effects appeared to be via interaction with an alpha 1 adrenergic receptor. In addition, it was found that alpha 1 receptor-mediated Na/H exchange in VSMC was increased by angiotensin II and inhibited by 12-O-tetradecanoyl phorbol-13-acetate (TPA). Adrenergic receptors have been shown to be coupled to both adenylate cyclase and to inositol phosphate release (Leeb-Lundberg, L. M. F., S. Cotecchia, J. W. Lomasney, J. F. DeBernadis, R. J. Lefkowitz, and M. G. Caron, 1985, Proc. Natl. Acad. Sci. USA, 82:5651-5655.). It was found that catecholamines increased AMP levels in the potency order isoproterenol greater than norepinephrine greater than epinephrine and the receptor involved was a beta adrenergic receptor. Since these findings did not parallel the results obtained for catecholamine stimulation of Na/H exchange, an increase in AMP levels was probably not the mechanism by which major pathway for catecholamine-stimulated Na/H exchange in VSMC (via the alpha 1 receptor) was activated. When the effects of catecholamines were measured on inositol phosphate release, the potency order for catecholamine stimulation was epinephrine greater than norepinephrine greater than isoproterenol, and the receptor involved was an alpha 1 adrenergic receptor. In addition, angiotensin II increased and TPA inhibited catecholamine-stimulated inositol phosphate release. Since these findings paralleled the results obtained for catecholamine stimulation of Na/H exchange, inositol phosphate release may be the mechanism by which the major pathway for catecholamine-stimulated Na/H exchange in VSMC (via the alpha 1 receptor) was activated.

Sign in / Sign up

Export Citation Format

Share Document