can someone help me with these 3 questions with explanations, tnx! 4. Questions:

Question

can someone help me with these 3 questions with explanations, tnx!

4. Questions: Q#1. What is the average MW of an amino acid in BSA and in lysozyme (the sequence of lysozyme is on page 14 in the lab manual; BSA bovine serum albumin has 582 residues and a MW of 66,296)? Are these numbers close to 110 gm/mole, the commonly used value described in the recitation lecture? Based on your calculations, is the number of peptide bond groups per 10 mg of protein approximately the same in both proteins? Q#2. If samples of two different proteins have equal concentrations of peptide groups, and if both proteins are unfolded at high pH and thereby make those groups accessible to the biuret reagent, should one get similar amounts of color for both samples in the biuret reaction? How did your results compare with this prediction? Q#3. Does DNA react with the biuret reagent? Does DNA enhance, inhibit, or not affect the reaction of the biuret reagent with peptide groups? Tell how your data support your answers. 92

Explanation / Answer

Ans1) Molecular weight of BSA = 66296 MW.

BSA has 582 residue, by taking 110 MW an average for every residue, we get = 66296/ 582 = 113.9 MW

These number of molecular weight are closed to the average 110 MW/mole but it is not exact.

Ans 2) The basic chemistry of the Biuret reaction is that it react with the peptide bond. If both the protein has same number of residue then the total number of peptide bonds present in the reaction issame. So, equal number of peptide bond will be present and equal amount to react with the reagent. So, it can be stated that equal amount of color will be absorved by the peptide bond in each protein.

Ans 3) DNA does not react with biuret reagent. DNA does not have peptide group where its react with the biuret reagent.

If DNA is attached with a peptide group C=O whose Oxygen atom is free then it can react with the Biuret reaction.

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