LIFE 107 - Practical 7 - Lecture notes PDF

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Covers membrane charge, lectin binding and 96 well plates....

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LIFE 107 -PRACTICAL 7 MEMBRANE CHARGE: SUGARS Acidic groups have (-) charge Amine groups that have (+) charge Cell surface glycans may carry a net charge

POLYSACCHARIDES Phosphate on phospholipid has (-) charge Can form ester bonds with serine, choline ad inositol. Sugars covalently bonded with to fatty acids Phospholipids and glycolipids may carry a net charge.

LECTIN BINDING: LECTINS – proteins that cross link carbohydrates. Sugar polymers are attached to proteins in the cisternae of the ER. They must have at least 2 sugar binding sites before they can cross link red cells.   

Multiple binding sites to recognise specific sugars on the surface of red blood cells. Due to this, the other end of a lectin can bind to another sugar molecule. This is cross linking.

However, if a sugar is present in high concentrations surrounding the red blood cells, lectin binds to this sugar rather than one attached to a sugar on a red blood cell = no cross linking and forms a ring due to aggregation.

96 WELL PLATES: COLUMN A = no lectin as a control but does have PBS. COLUMN B-H = have lectin.  

B has the lowest concentration of lectin. H has the highest concentration of lectin.

GALACTOSE  does not stop the cross linking. MANNOSE  more effective than glucose at binding to lectin since its better than glucose at stopping the cross linking. FUCOSE  no evidence of it binding to lectin as it does not prevent cross linking....