What would happen if...?

It would eventually reach a peak because the ratio of enzyme to substrate will be skewed. The only substrates I can see would work here would be pure oxygen and pure hydrogen.

2 H2 (g) + O2 (g) 2 H2O (l) H = –571.6 kJ (not sure how correct this is). I'm assuming that as soon as the chemical is formed, it would destroy the rest of the enzymes present, preventing it from moving forward. As a result, my predictions is that there wouldn't be a "fire hazard by mixing an enzyme powder +  substrate that when combined form HP."

There's an enzyme which converts fatty acid into hydrogen peroxide (Acyl-coa oxidase and fatty acid oxidase I think they were named?). the human metabolome database clearly lists HP as an enzymatic byproduct. what do you mean by '' I'm assuming that as soon as the chemical is formed, it would destroy the rest of the enzymes present''?

2 hydrogen peroxide is a byproduct of fatty acid metabolism. its not in high concentration but I'm wondering if the enzymes would survive their own reactions if they had enough substrate to produce concentrations of hydrogen peroxide above, say, 20%

because in this scenario I would be dumping a powder of this enzyme into a solution of its substrate with no catalase in the solution. just 70% water and 30% its substrate.
Logically, due to the concentrations present,HP would be created very rapidly. thermal denaturation above boiling temperatures denatures protein within nanoseconds. Does the same apply for chemical denaturation?

No there isn't.

mmmm yes there is.
http://www.madsci.org/posts/archives/1999-09/938519528.Bc.r.html

D-amino acid oxidase and acyl-CoA oxidase
as well as Polyamine oxidase http://www.ncbi.nlm.nih.gov/pmc/articles/PMC166856/

You're saying there is an enzyme that converts this:



to this:

Yes!

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC166856/

More than one actually.. Polyamine Oxidase, Acl-Coa oxidase, D-amino acid oxidase..

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC166856/

This is for plants

Acl-Coa oxidase, D-amino acid oxidase exist in humans.

Where is it produced? I.e. what tissue/organ?

The Human Metabolome database doesn't say that.
But it IS created in human cells by enzymes.

Different tissues express different proteins, so it does matter quite a lot. That's why our brain looks different than our hand - both are human cells.