Difference between revisions of "User:Timothy L. Foley/Notebook/refolding matrix/2009/10/13"

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{| {{table}}
| align="center" style="background:#f0f0f0;"|'''Buffer'''
| align="center" style="background:#f0f0f0;"|'''molecular weight'''
| align="center" style="background:#f0f0f0;"|'''stock solution'''
| align="center" style="background:#f0f0f0;"|'''volume'''
| align="center" style="background:#f0f0f0;"|'''mass'''
| align="center" style="background:#f0f0f0;"|''''''
| MES||195||500||50||4.875||g
| HEPES||238.3||500||50||5.9575||g
| TRIS||121.1||500||50||3.0275||g
| CHES||207.3||500||50||5.1825||g

Revision as of 11:56, 13 October 2009

Owwnotebook icon.png Refolding Matrix <html><img src="/images/9/94/Report.png" border="0" /></html> Main project page
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In the beginning there was Jack

getting started here... The background reading I have done that will weigh heavy today: The Pierce Refolding Kit Instructions[1] that detail the 9 buffer components in their kit, which are:

reducing agents
divalent cations
high [NaCl]
guanidinium chloride (GnCl)

also contained in the kit is an unreleased "Refolding Guide" that comes with the ProMatrix kit an is not available electronically... it would be nice to read this, but C'est la vie!

A paper on High throughput automated refolding [2] that describes a 96 well matrix of buffer conditions they developed for structural genomics projects for Mtb and Viruses.

Finally, Vertex Pharmaceuticals [3] fills the gaps and describes the use statistical software to generate a fractional factorial screen; application of light absorption to measure protein precipitation (λ 390nm); and most importantly statistical analysis of the data (both precipitation and enzyme activity)from the fractional factorial matrix to draw conclusions and further direct optimization.

Designing Our Matrix

The problem with any matrix report, is that they are packed full of misc. chemicals that are either not in house, or prohibitively expensive... it is my experience to find a way to furnish results that are desired first, then ask for $$$ chemicals to improve future experiments second...
This excludes:

all Non Detergent SulfoBetaines (NDSB's) that can or cannot be important
a-cyclodextrin and methyl-B-cyclodextrin (NB: B-cyclodextrin that we have in house is not soluble in H2O.)
fancy detergents (lauryl maltoside)
N-lauryl sarcosine (iFOLD kits)
FoldACEs (iFOLD series 3 kit)
disco reducing agents (BMC: bis-mercaptoacetamide cyclohexane)


From Willis' [3] report, buffer pH, detergent, and NDSB 201 were important for some proteins,

So, our matrix will include an expansion of pH, and various detergents around that may or may not help (it's a screen for a reason) additives that are not NDSB's that may help, and some other stuff I like to hypothesize about.

The conditions we will screen follow:

pH/ Buffer
5.5 MES
6.5 MES
8.2 TRIS
9.0 CHES

I replaced BORATE pH 9.5 from [3] with CHES to alleviate complications that will arise during reagent preparation, since borate is only marginally soluble in water, and cannot be prepared as a 10X stock (500 mM).

detergents/ concentration
triton X 100
tween 80

NB: NONE is a category for all subsequent categories, because it must be included for matrix generation

reducing agents/ concentration


divalent cations (2 Mg++/ 0.1 Ca++)
PEG 3350
NaCl/KCl (high ionic strength)

Why BSA? this is my screen, and a I want to try something wacky.

Stock Solutions

it is important to make sure that your stocks are at concentrations appropriate such that an all positive sample (e.g. one having all possible components) does not have a volume greater than your total volume for the experiment

here is the table I cooked up to figure out what "X" concentration I would need to make everything work, taking into account certain characteristics (e.g. if 20% glycerol will be the final concentration, then i cannot achieve more than a 5X stock solution)

component stock solution relative volume
Buffer 10X 10
detergent 100X 1
amino acids 5X 20
GnCl 10X 10
Ligand 10X 10
PEG 100X 1
Glycerol 5X 20
Salt MIX 10X 10
BSA 10X 10
Reducing agent 100X 1
total 93

NB: I used the totally wicked excel2wiki converter for the table code

so we are set.

component concentrations from [3] units interconversion
Buffer 50 mM
detergent 0.5 mM ~0.06%
amino acids 550 mM
GnCl 550 mM
Ligand 100 uM
PEG 0.06 %
Glycerol 20 %
Salt MIX 264/11 mM Na/K
BSA 10 mg/mL
Reducing agent 5 mM

stock solutions we will need:

stock solution concentration units
Buffer 500 mM
detergent 6 %
amino acids 5500 mM
GnCl 5500 mM
Ligand 1000 uM
PEG 6 %
Glycerol 100 %
Salt MIX 2640/110 mM Na/K
BSA 100 mg/mL
Reducing agent 500 mM


Buffer molecular weight stock solution volume mass '
MES 195 500 50 4.875 g
HEPES 238.3 500 50 5.9575 g
TRIS 121.1 500 50 3.0275 g
CHES 207.3 500 50 5.1825 g



  1. http://www.piercenet.com/files/1453as4.pdf [Pierce]
  2. Vincentelli R, Canaan S, Campanacci V, Valencia C, Maurin D, Frassinetti F, Scappucini-Calvo L, Bourne Y, Cambillau C, and Bignon C. High-throughput automated refolding screening of inclusion bodies. Protein Sci. 2004 Oct;13(10):2782-92. DOI:10.1110/ps.04806004 | PubMed ID:15388864 | HubMed [Vincentelli]
  3. Willis MS, Hogan JK, Prabhakar P, Liu X, Tsai K, Wei Y, and Fox T. Investigation of protein refolding using a fractional factorial screen: a study of reagent effects and interactions. Protein Sci. 2005 Jul;14(7):1818-26. DOI:10.1110/ps.051433205 | PubMed ID:15937284 | HubMed [Willis]
All Medline abstracts: PubMed | HubMed