LMPG is a phospholipid-like detergent. Relative to other micelles and also to is

Question

LMPG is a phospholipid-like detergent. Relative to other micelles and also to isotropic bicelles, LMPG micelles were found to yield NMR spectra of superior quaility for this protein. NMR samples of C99 contained 0.25 mM protein dissolved in buffer A (10% (w/v) LMPG in 100 mM imidazole (as imidazolium hydrochloride), and 10% (v/v) D2O, pH 6.5). NMR data were collected at 45 dergrees celsius.

Explain how you would prepare 80 mL of buffer A at the target pH. Look up molecular weights and provide in grams, how much of each component needs to be added, or if added from a concentrated stock, the required volume. What will the pH of the solution be if you initially dissolve the buffer in 1/2 the target volume? (imidazolium, pka = 6.90)

Explanation / Answer

Using Hendersen-Hasselbalck equation for buffers,

pH = pKa + log(bae/acid)

let a moles of imidazolumHCl is added

6.5 = 6.9 + log(0.1 M x 0.08 L - x/x)

0.008 - x = 0.4x

x = 0.0057 mols

mass of imidazoliumHcl needed = 0.0057 mol x 104.54 g/mol = 0.60 g

moles of imidazole needed = 0.008 - 0.0057 = 0.0023 mols

mass of imidazole neede = 0.0023 x 68.08 = 0.16 g

Related Questions

Navigate

• Browse (All)
• Browse L
• Subjects

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