User:Sarah Burkhard/Notebook/471 Nano Notebook/2017/03/21: Difference between revisions
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|style="background-color: #EEE"|[[Image:owwnotebook_icon.png|128px]]<span style="font-size:22px;"> Project name</span> | |style="background-color: #EEE"|[[Image:owwnotebook_icon.png|128px]]<span style="font-size:22px;"> Project name</span> | ||
|style="background-color: #F2F2F2" align="center"| | |style="background-color: #F2F2F2" align="center"|[[File:Report.png|frameless|link={{#sub:{{FULLPAGENAME}}|0|-11}}]][[{{#sub:{{FULLPAGENAME}}|0|-11}}|Main project page]]<br />{{#if:{{#lnpreventry:{{FULLPAGENAME}}}}|[[File:Resultset_previous.png|frameless|link={{#lnpreventry:{{FULLPAGENAME}}}}]][[{{#lnpreventry:{{FULLPAGENAME}}}}{{!}}Previous entry]] }}{{#if:{{#lnnextentry:{{FULLPAGENAME}}}}|[[{{#lnnextentry:{{FULLPAGENAME}}}}{{!}}Next entry]][[File:Resultset_next.png|frameless|link={{#lnnextentry:{{FULLPAGENAME}}}}]]}} | ||
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==Objectives== | ==Objectives== | ||
* | * UV-Vis prepared solutions | ||
* Prepare ~ 50mM His solution | |||
[[Image:Screenshot 2017-03-21 at 2.03.24 PM.png]] | |||
==Observations== | ==Observations== | ||
* The capped and the non-capped Arg at pH 14 show purple color | * 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 | * Cys-Arg 10 times ratio and the 5 times ratio show white precipitate | ||
* capped pH 8 and 10 show yellow/orange color | * 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 absorbs at 290 nm. | |||
==Discussion== | ==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. | Yellow in specific often indicates amino groups (N=O) . This could be further confirmed using IR spectroscopy. | ||
Further, the fact that NPs formed above pK2, where the amino acid is negatively charged (above pH 13.2) , leads us to run further tests with Histidine, which has a lower pK2 and therefore a wider range of pH we can test. | |||
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 | |||
'''We will run Histidine at pH 4, 7 , 10, 12, and 14 .''' | |||
'''Make graph of Arg absorbance at different pH''' | |||
Latest revision as of 02:16, 27 September 2017
Project name | Main project page Previous entry Next entry |
Objectives
Observations
DiscussionThe 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. Further, the fact that NPs formed above pK2, where the amino acid is negatively charged (above pH 13.2) , leads us to run further tests with Histidine, which has a lower pK2 and therefore a wider range of pH we can test. 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
Make graph of Arg absorbance at different pH
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