Is MSG able to penetrate meat like chicken breast and steak when dissolved in a brine? I am trying to figure out whether adding MSG to a water based brine will allow the MSG to 'penetrate' the meat. I know it is soluble, but I'm not sure whether this means it will be able to diffuse into the meat in the same way regular salt does. I remember reading a claim (a comment online) that the size of the molecules involved in the MSG means it will not work.
Is this true? I am hoping to actually try this out, but it would be helpful to know the basic food science/chemistry behind it to figure out the optimal concentrations etc.
Yes, MSG will penetrate, and it appears to diffuse about 1/3 as fast as table salt. You will learn a lot from this link.  You'll need to scroll down quite a bit, or search the page for MSG.