Denaturation of enzymes

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Denaturation of enzymes

Post by nigel123 » Thu Mar 17, 2005 5:27 am

When an enzyme is placed in temperatures too high or unfavourable pH, it denatures.

Can someone explain to me the changes in shape and tertiary structure of the enzyme during denaturation, and the breaking of hydrogen bonds part?


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Post by Poison » Thu Mar 17, 2005 1:30 pm

Enzymes are proteins.
The tertiary and quaternary structures of proteins are fragile and tend to come apart under conditions less than optimal. This loss of shape , called denaturation, occurs as ionic and H- bonds break. Salty envionments (excess Na+ and Cl-), acidic envionments (too much H+), and alkaline envionments (too little H+ ) Break ionic and H- bonds interfering with their electric charges. Heat causes movement within molecules, which disturb their relatively weak bonds. Once denaturated, most proteins will not re-form their original shape.
(Proteins usually exposed to unusual envionments have tertiary and quaternary structures held by covalent bonds, between the sulfur atoms of cysteine. )

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Post by osmosischild » Sun Dec 24, 2006 2:57 pm


You helped meeeeeeeeeeeeeeeeeeeee :]

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Re: Denaturation of enzymes

Post by carmenh » Fri Feb 27, 2009 10:21 pm

So in response to what poison wrote, I need a little more elaboration upon the denaturation and renaturation.

You said that most proteins don't reform their natural shape. Could this be due to the fact that you need chaperones and other such helpers to achieve a proteins natural conformation? Or could it be due to the free energy. Once a protein or enzyme is denatured, there is an excess of free energy, correct? What if, according to the stability of individual molecules and individual sections, that bonds reform in a different order than when the protein was first created?

Say, for example, you have the covalent bonds (along the entire primary structure) that form first, followed by disulphide bonds. What if a single disulphide bond were to form first, before all the covalent bonds had finished creating the primary structure? Is this something that would interfere with renaturation?

If I'm understanding it right, it seems that this is a very delicate process in which there are many variables that could interfere with creating structure. So how is it we can still survive with such a large trial and error process going on? Is it just sheer number and statistics?

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