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Calculating Protein Concentration

Calculating Protein Concentration - Protocols and Methods Forum

Calculating Protein Concentration - Post Any Protocol, Method, Technique, Procedure or Tips / Troubleshooting for any Molecular Biology Technique.


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  #1  
Old 01-17-2008, 12:46 PM
Yvonne Couch
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Default Calculating Protein Concentration



I have two proteins of different molecular weights, how do I calculate the
molarity of any solution I dissolve them in? For example Protein 1 is 15kDa
and 1mg is dissolved in 1ml of water, how do I calculate how many moles this
is?

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  #2  
Old 01-17-2008, 04:31 PM
DK
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Default Calculating Protein Concentration

In article <[Only registered users see links. ].net >, "Yvonne Couch" <[Only registered users see links. ].ac.uk> wrote:

For this calculation you'll need to learn how molarity is defined...



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  #3  
Old 01-17-2008, 07:40 PM
Tom Anderson
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Default Calculating Protein Concentration

On Thu, 17 Jan 2008, DK wrote:


Which, since Yvonne is a technician in a hurry, i shall (try to) explain.

Molarity, aka concentration, is the number of moles of something divided
by the volume it's in.

If you don't know the number of moles, but you know how much of the thing
you have by mass, and the molecular mass of it, you can work it out.
Molecular mass is defined as the mass of one mole of something (kinda),
with a dalton (Da) being one gram per mole, so you just divide the mass by
the molecular mass.

So, 1 mg of a 15 kDa protein is 0.001 g / 15000 g/mol = 0.000000067 mol,
or 67 nmol. 67 nmol / 0.001 l = 67 uM.

67 nanomoles may not sound like a lot, but don't worry, it's still 40
thousand million million molecules.

tom

--
Tom Anderson, MRC Laboratory for Molecular Cell Biology, UCL, London WC1E 6BT
(t) +44 (20) 76797264 (f) +44 (20) 76797805 (e) [Only registered users see links. ]

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  #4  
Old 01-18-2008, 09:02 AM
StewJW
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Default Calculating Protein Concentration

On 17 Jan, 12:46, "Yvonne Couch" <[Only registered users see links. ].ac.uk> wrote:

so 1 mg / ml or 0.001 g / ml

0.001 / 15 000 = 66.66 nmol /ml (66.66 x 10^-9 mole / ml)

or 66.66 x 1000 = 66.66 Ámol / L or 66.66 ÁM (M = Molar = mol / L)

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  #5  
Old 01-18-2008, 03:22 PM
DK
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Default Calculating Protein Concentration

In article <[Only registered users see links. ]>, StewJW <[Only registered users see links. ]> wrote:

Or without quantities at all:

15000 mg/ml = 1M
15 mg/ml = 1 mM
=> 1 mg/ml = 1 mM/15 = 0.06(6) mM ~ 67 uM
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  #6  
Old 01-18-2008, 05:40 PM
AK
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Default Calculating Protein Concentration

It is amazing to me that this basic question was honored here, perhaps since
she is from Oxford. I remember not too long ago a student was hammered to
death because of asking a basic question of plant extraction. UNFAIR.
AK

"Yvonne Couch" <[Only registered users see links. ].ac.uk> wrote in message
news:[Only registered users see links. ].n et...


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  #7  
Old 01-18-2008, 07:45 PM
WS
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Default Calculating Protein Concentration

Dear AK,

seems that even at famous Oxford either the students or the teaching
have become worse...

Actually, this stuff is a sort of "first day, first lesson's
knowledge" in
almost any subject related to natural science. More to worry, a PhD
(!) student in my lab asked me exactly the same question a few days
ago, too. The funny thing is, when I told him to treat the problem the
same way as to make a sodium chloride solution, he could solve the
problem instantly.

What makes me especially worry is that this kind of questions in this
NG constantly seems to increase. I do not think it just lazyness, as
for a newbie to find this NG on the web, usually, you need to have
done some googling before on behalf of your actual problem. My
impression is that many of those girls&guys really don't know how to
solve their problems and somehow manage to discover the bionet.

Hey students, please comment on this, your opinion and experience is
wanted here!!! Did nobody teach you these things, do you not know
where to find this kind of textbooks and lessens or are you really
just lazy?

Hey experts, is there any book/website/pdf/etc like {Mathematics,
Chemistry, Logical Thinking, Statistics, Planning Experiments and
Evaluating Experimental Data} in {Biochemistry, Molecular Biology,
Life Science} for Dummies?

Any ideas?

Wo


On 18 Jan., 18:40, "AK" <[Only registered users see links. ]> wrote:


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  #8  
Old 01-18-2008, 10:30 PM
Jayakumar, R
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Default Calculating Protein Concentration

Well.. The issue of poor mathematical knowledge arises from the basic
levels of education. At school levels and even at college levels, the
use of calculators have become rampant and necessary. Students should
be asked to work mathematical problems with their head, as we all used
to do and as several older scientists still continue doing so. using
calculators are making that part of the brain redundant and creating
these problems in students. Ban calculators at least up to high school
levels and the next generation of students would be more mathematics
savy.
Jay


-----Original Message-----
From: [Only registered users see links. ]
[mailto:[Only registered users see links. ].indiana.edu] On Behalf Of WS
Sent: Friday, January 18, 2008 2:45 PM
To: [Only registered users see links. ]
Subject: Re: Calculating Protein Concentration

Dear AK,

seems that even at famous Oxford either the students or the teaching
have become worse...

Actually, this stuff is a sort of "first day, first lesson's knowledge"
in almost any subject related to natural science. More to worry, a PhD
(!) student in my lab asked me exactly the same question a few days ago,
too. The funny thing is, when I told him to treat the problem the same
way as to make a sodium chloride solution, he could solve the problem
instantly.

What makes me especially worry is that this kind of questions in this NG
constantly seems to increase. I do not think it just lazyness, as for a
newbie to find this NG on the web, usually, you need to have done some
googling before on behalf of your actual problem. My impression is that
many of those girls&guys really don't know how to solve their problems
and somehow manage to discover the bionet.

Hey students, please comment on this, your opinion and experience is
wanted here!!! Did nobody teach you these things, do you not know where
to find this kind of textbooks and lessens or are you really just lazy?

Hey experts, is there any book/website/pdf/etc like {Mathematics,
Chemistry, Logical Thinking, Statistics, Planning Experiments and
Evaluating Experimental Data} in {Biochemistry, Molecular Biology, Life
Science} for Dummies?

Any ideas?

Wo


On 18 Jan., 18:40, "AK" <[Only registered users see links. ]> wrote:

extraction. UNFAIR.


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  #9  
Old 01-19-2008, 02:11 AM
DK
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Default Calculating Protein Concentration

In article <[Only registered users see links. ]>, WS <[Only registered users see links. ]> wrote:

One would have hoped that no one with a potential to be admitted
to any college should be able to graduate from high school without
understanding such things.

(On the other hand, there was an MD/PhD guy here about 7-9
years ago who clearly made no distinction between mM and mmol;
he is probably treating some patients right now!).


Nope, it's the "protocols" (as in kits and black boxes). Most
undergrads and many grads that I've seen lately have this funny
notion that science is about *doing* things. As in - do cloning, do
purification, do kinetics, do this and that - and, after all is done,
the paper is ready. And for most of these things there are kits
and protocols - which one just needs to follow!

That there has to be a cranial input somewhere in the process
frequently never comes into equation.

Then again, when > 80% of what PIs need is sheer monkey
lab labor, how can any of this be surprising? Say "postdoc
glut"...

DK
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  #10  
Old 01-24-2008, 08:45 PM
Dr Engelbert Buxbaum
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Default Calculating Protein Concentration

Am 18.01.2008, 15:45 Uhr, schrieb WS <[Only registered users see links. ]>:



I just entered "biochemical calculation" in Amazon and got 234 results
back. Even excluding more advanced stuff (Bioinformatics, Biophysics)
there are quite a few that deal with elementary lab type calculations.
Shows how big the need really is. The one by Segel I remember seeing in
the departmental library when I was a student:

Irwin H. Segel: Biochemical Calculations: How to Solve Mathematical
Problems in General Biochemistry, Wiley, 2nd Edition 1976
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