enzyme inhibitors

[the red shark]

I am just wondering if anyone could explain how to know the diffference between competitive and non-competitive enzyme inhibitors to determine which inhibitors act as potentiators.

Example: For enzyme CYP2D6 methadone is listed as both as substrate and inhibitor and methamphetamine as a substrate, how would this affect the metabolism of both substances if both were consumed?

Thanks

 

[hussness]

A good answer to some of the questions you posed can be found on http://www.umdnj.edu/biochweb/education/bioweb/FAQs.html

Also check the Erowid/Bluelight Neuropharmacology Text (Sticky).

 

[kidamnesiac]

anything that is a substrate is also an inhibitor at [high], because your body only has a limited number of a given enzyme and if it is all busy breaking your compound down, it can't be breaking anything else down. For some compounds this means hugemongous amounts of a given substrate, like dmt and mao. for others, it may only take a nanogram and the enzyme is out of commission for days (there are now femtomolar inhibitors!) It all depends on the residency time in the enzymes pocket before and after catalysis, how many times it must go in the enzyme before actual catalysis takes place (somethings just don't fit right most of the time) and the speed of the speed of the enzyme naturally, along with several other minor/physiological factors. These three things can be summed up as the Kd/Ka, the catalytic efficiency (is there a proper K for this, I'm spacing), and the Kcat or Vmax, depending on who you're talking to.

The link does a better job but this is a brief overview that times it up and puts it simply.

 

[the red shark]

thank-you

 

[LuxEtVeritas]

oddly (to my thought anyway) is huge doses of PEA by itself do nothing to make it active even though it is a MAOB substrate

Even at say 2g there is not enough MAOB-I to render it active in similar fashion to use with a MAOB-I like selegiline

in the literature there appear to be some pM and maybe fM potency MAOB-I, though i do not have access to the full texts to really see what is what

 

[Beenhead]

Non comp. inhibition occurs when a substrate binds to a site that is not the normal catalytic site, this changes the shape of the enzyme and turns it off