[Borek]

What is their use in biochemical experiments?

[Mitch]

EDTA is used to titrate metals in Chemistry.

[Borek]

What is EDTA used for in analytical chemistry I know However browsing the web in recipes for the solutions used in biochemistry experiments I often see buffers plus EDTA plus magnesium chloride. Buffer use is obvious, but what role plays MgCl₂? And why is magnesium chelated with EDTA?

Same problem, additional question: sometimes succrose is used in high concentrations. Is it used just to obtain high viscosity, or something else?

[savoy7]

NOTE:  not best answer - just from the top of my head - you should probably research more -

this is really simplified
Basics -
Mg ions can "activate" some enzymes

EDTA - chelates - picks up Mg ions

Assays - depends on what you are doing - isolating DNA, cutting it, ligating it. copying it, etc
so - you want to store DNA - it is usually done in a buffer with EDTA - one would not want enzymes to break down DNA

Now you want to "cut" the DNA - you might need Mg to "activate" the enzyme, so you have to added Mg - note it is usually more because it has to conpensate for the EDTA the DNA was stored in

[lemonoman]

I am told that,

"So basically um, when you do a reaction Mg²⁺ is used as energy in an experiment, like PCR (polymerase chain reacction).  So in order to stop the reaction, you add EDTA which complexes the Mg²⁺ so you don't have any energy to be used and stops the reaction"

Hope that helped.  It's a quote from a 'personal communication'...i.e. I asked my friend Mike

[Borek]

Mg²⁺ as a source of energy?

Are we talking about the same chemistry and the same periodic table?  

[lemonoman]

Don't worry.  I slapped Mike upside the head for that one.

I've never taken a biology course in my life.  And henceforth promise to stay out of this section of the forum...no matter who my friends proclaim to be.

Cheers!