How does sodium acetate precipitation for protein purification works?

For a project we purify polygalacturonase (pectinase) out of a fungus culture.
We take 40 ml of cultured broth and add 40 ml sodium acetate 0.05M
This solution is then filtrated.
The filtrate is then used so i suppose it will contain the polygalacturonase enzyme. So what does the acetate do? Probably not precipitate the enzyme we need because it's in the filtrate.

Question

How does sodium acetate precipitation for protein purification works? 

For a project we purify polygalacturonase (pectinase) out of a fungus culture. 
We take 40 ml of cultured broth and add 40 ml sodium acetate 0.05M
This solution is then filtrated.
The filtrate is then used so i suppose it will contain the polygalacturonase enzyme. So what does the acetate do? Probably not precipitate the enzyme we need because it's in the filtrate.

abb0t · Answer

helps with solubility.

abb0t · Answer

I'm assuming that it's similar to ammonium sulfate preipitate which i've worked with before in lab.
1. increases effects of protein solubility 
2. stabilizes the protein stability. 

since proteins usually have an hydration outter shell which protects them keeping them soluble.

thomaster · Answer

ammoniumsulfate is used later to salt out the proteins. I'm only wondering why it's called 'sodium acetate precipitation' since it's not the intention to precipitate enzymes. Only thing i could come up with is precipitating DNA but i don't think there's much DNA in crude enzyme.

abb0t · Answer

Yeah, i think it's to protect the protein from denaturing. Are you performing a dialysis?

thomaster · Answer

after ammoniumsulfate precipitation yea

abb0t · Answer

yeah. i think ammonium is better for smaller fragments. cuz ammonium sometimes inhibits some kinases since you're working with DNA, right? I just re-read everything haha. my bad.

abb0t · Answer

the role of salt, i'm going to assume, is to bind with DNA in order to precipitate, which is your objective from what I read. you know DNA contains negative charge with it and they repel each other, and the salt with positive charge will neutralize some of the negative charge. then they can easily precipate.

thomaster · Answer

Yes but it is not the target to precipitate DNA since there is no DNA in the cultivated broth, only proteins. I guess the NaAc is only for buffering, stabilizing the protein. Then with ammosulf precipitation it will be salted out. 
Thanks for your help by the way :)

abb0t · Answer

Yeah. best of luck with your lab. cheers!