User:Sarah Burkhard/Notebook/471 Nano Notebook/2017/03/21

From OpenWetWare
Jump to navigationJump to search
Project name <html><img src="/images/9/94/Report.png" border="0" /></html> Main project page
<html><img src="/images/c/c3/Resultset_previous.png" border="0" /></html>Previous entry<html>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</html>Next entry<html><img src="/images/5/5c/Resultset_next.png" border="0" /></html>

Objectives

  • UV-Vis prepared solutions

Observations

  • The capped and the non-capped Arg at pH 14 show purple color
  • Cys-Arg 10 times ratio and the 5 times ratio show white precipitate
  • capped pH 8 and 10 show yellow/orange color
  • The non-capped shows a peak at 580 nm. The capped shows a peak at the same wavelength, but with muss less intensity.
  • The Cys-Arg mix absorbs at a wavelength around 370 nm, and shows a shoulder around 240 nm.
  • The capped pH

Discussion

The yellow color from the capped Arg may come from a reaction of the N-cap, which has a carboxamide group. Yellow in specific often indicates amino groups (N=O) . This could be further confirmed using IR spectroscopy.

Histidine will have a negative one charge at pH above 8.97.

pKa1 1.78 (carboxylic group will be protonated only at pH below 1.78 ) pKa2 8.97 (amine will be protonated only at pH values below 8.97 ) pKaR 5.97 (amine in R chain will be protonated at pH values below 5.97)

charges: below 1.78: charge is 2+ 1.78 - 5.97 : +1 5.97 - 8.97 : 0 above 8.97  : -1

1.78

8.97

5.97

7.64




Retrieved from "https://openwetware.org/mediawiki/index.php?title=User:Sarah_Burkhard/Notebook/471_Nano_Notebook/2017/03/21&oldid=978977"