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Effect of harmaline on rat intestinal brush border sucrase activity

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Title Effect of harmaline on rat intestinal brush border sucrase activity
 
Creator Kaur, Navneet
Kaur, Jyotdeep
Mahmood, Akhtar
 
Description 119-123
The effect of harmaline, a plant alkaloid
has been studied on rat intestinal brush border sucrase activity. Stimulation of
sucrase activity by Na+ was found to be pH-dependent. At neutral pH,
20 mM Na+ stimulated sucrase activity by reducing Km
by 30% while at acidic pH (5.2), the activity
increased 4-fold compared to Na+-free enzyme. At 1.0 mM,
harmaline

markedly inhibited (67%) the
enzyme activity at pH 5.2 in the absence of Na+.
However, inhibition was reduced in presence of 20 mM sodium, whereas 4.0
mM harmaline was required to inhibit the enzyme activity by 65%. In
the absence of Na+ ions, harmaline inhibition of sucrase activity
was of competitive type, but it changed to non-competitive type in presence of 20
mM Na+ at pH 5.2. Sucrase-harmaline
interactions as a function of pH, both in presence and absence of
Na+ revealed a shift in pH optima of the enzyme
towards a higher pH in presence of 4 mM and 1 mM
harmaline respectively. The observed inhibition was reversible in nature and was
only partially overcome by sodium, lithium, potassium, cesium, rubidium and ammonium
ions. These findings suggest that harmaline also inhibits rat brush border sucrase
and that the presence of Na+ site is not a pre-requisite for the
inhibition.
 
Date 2013-07-15T07:16:16Z
2013-07-15T07:16:16Z
2002-04
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://hdl.handle.net/123456789/19762
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJBB Vol.39(2) [April 2002]