Question

Explain from a molecular level, how changing the concentration of catalase affected the structure and function of catalase.

Answer 1

i dont understand why a change in concentration of an enzyme can affect its structure. I dont think it does, you would have to denaturalize the enzime in order to affect its structure. and about the function, enzimes could be regulated through feed back mechanisms, in this case, an excess of sustrate for catalasa (H2O2) could accelerate the reaction or the opposite if there is an excess of products: water and molecular oxygen

Answer 2

I'm not sure about this one but I know that catalase gets oxidised by the substrate (hydrogen peroxide) during the reaction then reduced again by the second molecule. There's a bit on Wikipedia about enzyme knietics and catalase is used as an example: http://en.wikipedia.org/wiki/Enzyme_kinetics

I hope this has set you off in the right direction

Answer 3

At its simplest, protein concentration has no effect on the structure of individual copies of that protein: individual proteins don't care how many others like them the cell has when they assume their structures (unless they are associated with each other as subunits of some larger complex in which case subunit conformation is a whole different ballgame).

At its slightly less simple, proteins are not static molecules. Associated with each protein is a conformational space which consists of all possible structures it can assume and in that context the structure that each individual copy of the protein does assume is a sample from that space. Most of those samples are very similar - but when there are many copies of a protein present, it is more likely that you start seeing small sub populations of proteins which sample different conformations. But not any more likely that an individual protein will have an unusual or energetically less favourable structure.

You could also consider the structural effects of post translational modification on individual copies of the protein. Plainly, covalent modification alters the conformational spaces available to individual copies of a protein. Often that modification is in response to factors like substrate/product ratios which depend at least partially on absolute levels and concentrations of that protein as already noted above.

So perhaps indirectly the structures of individual proteins or conformational sub populations of proteins can be related to protein concentration.