e pH of the lumen of a lysosome is pH-4.5. Lysosomes are organelles that digest
ID: 148106 • Letter: E
Question
e pH of the lumen of a lysosome is pH-4.5. Lysosomes are organelles that digest and remove rom cells. How is a protein, that normally functions at pH-7.2 and is held together by salt- bridges, affected when it enters a lysosome? Calculate the percentage of glutamic acid residues that would be protonated/deprotonated at pH 4.5. What is the charge on glutamic acid and lysine at plH-4.5. Would the salt bridge be stronger or weaker at pH-4.5 compared to pH-7.2?-13 pts NH -. pKa-3.9 ,- H3N pKa-10.0 HNExplanation / Answer
The normal activity of the Glutamic acid amino acid at 7 pH but is can very according to the pH in the solution.
Let's start the answer
In the cell we already know that lysosome can degrade the polypeptide chain or proteins with the effect of pH at lumen.
When a salt bridge that is made between a positive charge and a negetive charge amino acid is intered into the lysosomal lumen it show like a activity like adding acid , at that time many proton are present in the lumen that can easily attached to the COO- site of the salt bridge and can disrupt the salt bridge , and at that stage both amino acid is protonated lysine as well as Glutamic acid.
All the residue of glutamic acid become protonated at pH 4.5.
The charge on the Glutamic acid is 0 and the charge on the lysine residue is +1 we can easily understood with the structure of these two amino acid . Means in the case of Glutamic acid there are a COOH group in the side chain but in the case of lysine there are not then the lysine contain +1 charge.
The salt bridge become weaker because of protonated at the side chain of Glutamic acid is from the lumen pH .
Thank you
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