Re: What can we find between the two membanes of the nucleus enveloppe?

To my surprise I couldn't get substantial information to your question, so 
I suspect nobody has really looked into that. Here is what I have found:

1. Mitochondria:	The generation of ATP as energy source for the cell 
takes place at the inner double membrane. Most of the involved proteins 
face to the lumen of the mitochondrion. Some components, however, are 
facing to the intermembrane space, so that the intermembrane space provides 
an environment that permits electron transfer, which could be regarded as 
an indirect function. The composition of soluble components of the 
intermembrane space of mitochondria is apparently unknown.

2.Chloroplasts: 	The light reactions I and II take place at the inner 
double membrane, so the same principle as for the mitochondria is true for 
the plasts as well. Again, I could not get any information 
regarding the exact protein or ion composition of the intermembrane space.

3.Nuclear envelope: 	The inner double membrane of the nuclear envelope is 
stabilized by a meshwork of filaments, called the nuclear lamina. This 
membrane has in my opinion only a compartmentalizing function. The outer 
double membrane is associated with the endoplasmatic reticulum. As you may 
know, there are two forms of ER, a smooth and a rough ER. The rough ER is 
part of the protein synthesis machinery: proteins to be exported are 
synthesized into the lumen (cisternae; intermembrane space) of the ER where 
they are folded correctly (which may require additional proteins, so-called 
"chaperones"), sorted and subsequently transported to the golgi apparatus. 
The interior of the cisternae is to the best of my knowledge different from 
the cytoplasm. It is more like the extracellular space, more oxidative than 
the cytoplasm.

If you would like to get more information, I have found a number of 
webpages that may be of interest:

http://cellbio.utmb.edu/cellbio/nuclear_envelope.htm

http://ntri.tamuk.edu/cell/mitochondrion.html

http://www.sci.sdsu.edu/class/bio202/TFrey/Photosynthesis.html

http://www.botany.uwc.ac.za/Sci_Ed/std8/cells/

http://www.columbia.edu/~hjw14/NE.html

http://www.bact.wisc.edu/ScienceEd/mito.html


You may get more precise answers from those people who are named on these 
pages. Good luck


Andreas