Enzymes and pH Watch

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a.h123

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I know pH alters the enzymes tertiary structure, but how?

what do the OH- ions and H+ ions do to the structure/bonds in the tertiary structure

Jaustin827

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In short they break the hyrdogen bond on the side chains of the enzyme altering it's shape. It's these bonds that hold the enzymes shape and so without them the enzyme and active site lose their specialised shape.

More specifically depending on an enzymes location in the bosy the side chains have more Carboxyl or Amine functional groups. Depending on this the presence of more H+ or OH- will effect the pKa of the enzyme. Different enzymes work optimally at a different pKa so changing this effects the rate of reaction of the enzyme

HateOCR

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(Original post by a.h123)
I know pH alters the enzymes tertiary structure, but how?

what do the OH- ions and H ions do to the structure/bonds in the tertiary structure

Disturbs hydrogen and ionic bonds in the tertiary structure which means the enzyme loses its specificity therefore the turnover number drops.

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MezmorisedPotato

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For A level biology, all you need to know is the change in concentration of H+ or OH- ions from its optimum can cause a strain on the bonds holding the tertiary structure of an enzyme together ( for example, the ionic and hydrogen bonds). When this breaks, the shape of the tertiary structure changes which in turn changes the shape of an enzymes active site which leaves it denatured.

Kallisto

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(Original post by a.h123)
I know pH alters the enzymes tertiary structure, but how?

what do the OH- ions and H+ ions do to the structure/bonds in the tertiary structure

The pH value is defined by the ratio of OH- ions and H+ ions. If the pH is above or below neutrality (OH- ions and H+ are approximately equal in number), OH- ions or H+ are increased. That means a surplus of charged particles is in existence. The charges of those ions reacts with the bonds of the tertiary structure (ionic bond or hydrogen bond). That breaks the structure of the protein, it denaturates.

LadyLexa

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Above and below the optimum pH, the H⁺ and OH^-ions in acids and alkalis can break the ionic and hydrogen bonds that hold the enzymes tertiary structure together. This makes the active site change shape, so the enzyme is denatured.

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