On preparation of a solution of protein, you attempted to dissolve the substance

Question

On preparation of a solution of protein, you attempted to dissolve the substance in water, a suspension resulted. Drop-wise addition of NaOH solution, with stirring, eliminated the suspension. Addition of acid to the original suspension had no effect. Think about how PH affects the charge on a protein (therefore its solubility in aqueous) then explain the phenomenon described by speculating on the amino acid composition of the fictitious protein. Complete the following dilution table: the stock solution of protein is 1.0 mg ml^-1, the total volume of each diluted standard is 200 mu L (this proviso saves subsequent aliquoting of standards since 200 mu L has to be added to color development reagents for the Lowry method); you want four other dilutions of standard covering the range from 0.0 to 1.0 mg mL^-1: A sample was diluted 1/40 and 1/20 to determine the amount of protein by the Lowry standard curve method. The most dilute sample had an A_600 of 0.140, the other sample had an A_600 of 0 216. The correlation coefficient of the line of best lit (A_600 versus mu g/mu L protein) was 0.9999; the slope was 3.65 times 10^-13 mu L/mu g and the y-intercept was 0 07. How much protein (in mg ml^-1) was in the original solution?

Explanation / Answer

Q1.

As we add NaOH, a base, which will react with H+ ions and evnetually also react NH3+ + OH- = NH2 + H2O

So...

as we add NaOH, the charge must go from positive (+) to negative:

COOH turns to COO-

NH3+ goes to NH2

Related Questions

Navigate

• Browse (All)
• Browse O
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.