Two novel lectins were purified from the <I>Moraceae</I> plant <I>Morus nigra</I> or Black Mulberry. These lectins were named <I>Morus nigra</I> agglutinin I (MNA I) and <I>Morus nigra</I> agglutinin II (MNA II). Data obtained from carbohydrate inhibition studies indicated that MNA I specifically bound N-acetylgalactosamine and D-galactose, and in contrast, MNA II selectivity bound <I>α</I>-methyl-D-mannoside and D-mannose. MNA I is composed of two glycosylated α-chains and two <I>β</I>-chains, both of which share a high degree of amino acid sequence identity with the N-terminal regions of the <I>α</I>- and <I>β</I>-chains of the <I>Moraceae</I> lectins, Jacalin and <I>Macluar pomifera</I> agglutinin (MPA). MNA II consists of three dominant subunits, each of which has the same N-terminal amino acid sequence. This sequence shares a degree of N-terminal amino acid sequence identity with the <I>Moraceae</I> D-mannose binding lectin KM+ and the <I>β</I>-chains of Jacalin, MPA and MNA I. Glycosylation of the MNA II subunits was not detected. The binding characteristics of <I>Moraceae</I> lectins to the intestinal brush border were assessed using both <I>in vitro</I> and <I>in vivo</I> approaches. Initially <I>in vitro</I> studies using Brush Border Vesicle preparations were conducted. Thereafter <I>in situ</I> experiments using rat intestinal ligated loops were carried out. The <I>in vitro</I> and <I>in situ</I> binding studies showed that MNA I had a low binding capacity for the rat intestinal brush border, however Western blot studies illustrated that MNA I selectively bound to two rat intestinal brush boarder proteins. Initial <I>in vitro</I> data indicated that MNA II also had a low binding capacity for the rat intestinal brush border. However, additional <I>in vitro</I> and <I>in situ</I> studies showed MNA II bound extensively to the jejunal villi. Furthermore, considerable MNA II uptake into the jejunal enterocytes and lamina propria was detected.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:364707 |
| Date | January 2001 |
| Creators | Angel, Catherine Elizabeth |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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