Question

1. The process of calculating the % alpha-helix and beta sheets in a protein is called "deconvolution". true or false

2. You prepare a 1 M Tris solution at 25 °C with a pH of 7.5. Tris has a pKa = 8.06 at this temperature. You put the buffer in a refrigerator overnight because you want to use it at 4 °C. Unfortunately Tris is sensitive to temperature changes with a ∆pKa/°C = -0.031. What is the final pH of your cold Tris buffer? ( focus on sig figs)

a. 8.151 b. 8.15 c. 8.2

Answer 1

1. False; a deconvolution(grouping peaks into isotopomer envelopes) is a Software that uses an algorithm; first generates a large set of candidate isotopomer envelopes for a spectrum, then represents the spectrum as a graph, and finally selects its highest-scoring subset of envelopes as a heaviest path in the graph.

2. A. pH= 8.151

Note: the range of tris pH is 7.5-9

Ka value indicates how easily the acid loses a proton.

If Pka value is high then the acid is weak while Pka value low means the stronger acid. Pka value indicates the strength of the acid.

∆pKa/°C change is -0.031, so the total change in pKa from 25°C to 4°C will be 0.651