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biology coursework - enzymes

what are the factors that effect enzymes and also my teacher said to fina about how ions can effect enzymes but i cant find anything on that, anyone got any ideas?

btw im doing about catalase

thanx

Reply 1

Saagar

Enzymes effected by: Temperature, pH (which is where ions can play a part because a high concentration of H+ ions means a lower pH), Pressure, Surface area, Concentration of substrate, concentration of the actual enzymes. I'm sure theres one or two i forgot. :smile:

Reply 2

kookabura

Learnt this for an exam on monday - sure I've forgot most of it already, but I'll give it a go!

Temperature: Basically every enzyme has an optimum temp at which it will work. Too far below this and it will be too cold and become inactive. As the temp is increased and nears the optimum molecular motion increases resulting in more collisions and therefore more reactions. Too high and the temperture will damage the hydrogen bonds holding the secondary, teteriary and quaternary structure of the enzyme together and it will permanatley denature.

Concnetration of Substrate: The higher the the higher the rate of reaction, until all of the enzymes active sites become saturated and then the reaction rate plateaus off. The enzyme has a finite number of active sites, it can carry on increasing the rate of reaction unitl all of these are filled, then it becomes saturated, it can carry on reacting, just has to wait until a site becomes free.

PH: Again, similar to temp, each enzyme has an optimum, often but not always near neutral (stomach enzymes for example are nearer 2) too far above or below this will denature the enzyme. I can't remember this bit entirelly, but it is this bit that will relate to your ions I think.

Sorry I can't remember any more than that, trying searching on google, it will probably throw something up. Come to think of it now, how am I going to have passed that exam with so little knowledge!?!?!

Reply 3

selkie222

Heavy metal ions coud denature proteins. As you know some amino acid residues are charged, and they interact with each other under normal circumstances to hold the 3D shape of the protein together. Heavy metal ions could disrupt this specific 3D shape by interacting with the charged residues (loss of specific shape = loss of fuction = denaturation), and could also cause precipiation of the protein (probably a change of the protein from globular to fibrous forms).
http://www.elmhurst.edu/~chm/vchembook/568denaturation.html
http://members.aol.com/logan20/catalyst.html

A catalyse would very likely be a globular protein in order for it to be "dissolved" (better term is "form a colloid suspension") in water and be free to act on the substrate.

I think this isn't really in the A level syllabus so don't worry too much if you haven't learnt it for your test/exam... all the other factors affecting enzymes listed above are valid and would be enough to earn you the marks.

selkie

Reply 4

twilight

The easiest investigation to do is how the concentration of the substrate effects the rate of reaction of an enzyme. In your case the enzyme would be catalase and the substrate will be hydrogen peroxide.

With this investigation you can bring in collision theory and possibley enzyme saturation, (where increasing the concntration of the substrate, no longer increases the amount of hydrogen peroxide broken down).

Reply 5

idiopathic

What level is this for?

If A levels, then one of the factors would be heavy metal ions and continuing from Selkie's post the ions disrupt hydrogen bonding, disulphide bridges between amino acid side chains (R group/tertiary structure), which denature the enzyme because the enzyme changes its active site shape.