November 30, 2007
Lab Partner: Sasha-Kaye Graham
Experiment 6 : Lectin Agglutination
To study the agglutination pattern of different strains of Psuedomonas aeruginosa to different sialic acid-binding lectins.
The cell membrane of two strains of Psuedomonas aeruginosa, P22 and P201 were treated the sialic acid lectins SNA I, WGA, MAL and HAA to confirm the presence of sialic acid carbohydrates in the cell surface membranes of these strains. This was done by using two sets of samples-one treated with trypsin and the other without. The sample treated with trypsin showed agglutination for all lectins while the untreated sample showed little to no agglutination. A control was also used with the cells being incubated with buffer instead of lectins. The lectin pattern of agglutination varied based on the specific sialic acid available on each cell surface membrane of the two strains investigated.
Lectins are carbohydrate proteins or glycoproteins of non-immune origin which are often specific in the agglutination or binding to cell membrane glycoproteins similar in structure to the lectin. Lectins can be derived from the extracts of plants, animal viruses and microorganisms. They form precipitates with glycoconjugates and are useful for identifying or separating oligosaccharides with identical sugar compositions such as galactose, mannose or glucose. It can also be used in blood typing when they agglutinate or bind to glycoproteins on red blood cells. These agglutins can select types according to blood group activities utilizing sugar binding mechanisms. The real function of lectins in plants is still unclear but is believed to be the binding of glycoproteins on the surface of cells. Lectins containing sialic acid are also known to bind conjugate glycoproteins containing sialic acid. Sialic acid is a generic term for the N- or O-substituted derivatives of neuraminic acid, a nine-carbon monosaccharide. It is also the
References: Madigan, D., Martinko, J.M., Parker, J., Brock Biology of Microorganisms.(2003) Pearson education ltd. Pg 687. Caya, F., Charland, N., Gottschalk, M., Kellens J.T., Journal of Clinical Microbiology (1995) American Society for Microbiology, pgs 2220-2221.