Harmaline interaction with sodium-binding sites in intestinal brush border sucrase

The effect of harmaline on rabbit brush border sucrase has been studied at pH 6.8. An initial analysis in classical kinetic terms revealed harmaline to be a fully competitive inhibitor of the substrate, sucrose. In spite of this result however, the following hypothesis has been tested. Harmaline, which is positively charged in the physiological range of pH, might in fact compete, not directly with the substrate site, but rather with an allosterically-related sodium-binding site which has been postulated to be involved in the activation of sucrase by the alkali-metal ions (Mahmood and Alvarado, Arch. Biochem. Biophys. 168, 585, 1975). Because of its size, harmaline, when bound to the metal site, could at least partially overlap with the substrate site, thereby behaving as if it were an authentic fully competitive inhibitor of the substrate. This hypothesis appears to be confirmed by the fact that the alkali metals can completely reverse the inhibition caused by harmaline.

Tissue culture studies on Amaranthus viridis

Amaranthus viridis is a plant that is very widely distributed in our country, grows easily, and is eaten by low-income groups. It has been found that the proteins of this plant, like most other plants, are deficient in some essential amino acids. We were able to develop cultures from the cut-end parts of this plant tissue. The commonly used media were modified to achieve good and fast growth. Results have been obtained on the techniques, histology, chromosomal, and biochemical studies which indicate that the plant could be useful as a research tool to study problems in crop improvement at the cellular level.

Unusual surgical emergency in pregnancy

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