Question

When researches incubate whole red blood cells with lactoperoxidase, hydrogen peroxide and radioactive iodine I 125 and then separate the proteins in SDS gel, several radioactive lines are obtained cause iodine binds to prominent tyrosine and histidine residues outside the cell membrane.
When researches incubate whole red blood cells with galactose oxidase and reduce them with sodium borohydride that contains tritium (H-BH43) several radioactive lines are obtained which are just some of the proteins that have been marked with radioactive iodine , thus galactose residues stand out of the cell. 
a) Explain the difference in the number of proteins obtained in the two experiments above
b) Why the results of the second experiment do not reflect mark of all the sugars in the membrane? 
c) What results will be obtained if we conduct an experiment identical to that described in the question but with inverse vesicles (these are closed vesicles containing all membrane components but where the outer leaf of the membrane turns inward and inward leaf outward)?

Answer 1

a) In the first experiment RBC even after the addition of lactoperoxidase and hydrogen peroxide and radioactive iodine 95% of the cells remain intact but after the experiment, there is a reduction of good cells/proteins which are actually the RBC cells. The haemoglobin in the RBC is made up of iron and amino acids which are inhibited by the tumour cells. In the above experiment hardly 10% of the protein is obtained.

In the second experiment as the reaction is a reduction process but the tumour cells are damaged and therefore there can be an increase in the number of protein from 8-16 microgram/millilitre.

B). The sugar components galactose and lactoperoxidase are used in the experiment to react on tumour cells. Therefore they either don't react or reduce them but do not increase the sugar content of the cell. Where membranes are concerned they are a just epithelial layer of cells are therefore would discharge outside whatever sugar molecules get inside.

C) Where vesicles are concerned they are just epidermal or mesodermal cells, therefore the sugar compounds will not react and they will degenerate if they are dipped long in hydrogen peroxide.