Enzyme lecture summary PDF

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Enzymes...

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Biochemistry Enzymes

Enzymes as Biological Catalysts •Enzymes are proteins that increase the rate of reaction by lowering the energy of activation •They catalyze nearly all the chemical reactions taking place in the cells of the body. •Not altered or consumed during reaction. •Reusable

•Enzyme molecules contain a special pocket or cleft called the active sites.

Some enzymes are simple enzymes- functional by themselves as a protein- eg:pepsin Complex= Functional enzyme= holoenzyme- made up of cofactor and apoenzyme Cofactor- non protein portion (activator)-Apoenzyme- protein portion (inactive)

COFACTORS: -coenzymes - loosely binds to apoenzyme(vdws) eg:vitamins or compound derived from vitamins.

-prosthetic groups- binds a lot stronger to apoenzymes (covalent bonds)

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Cofactors induce a confirmational change within the apoenzyme

Lock and key vs induced fit

Active site is rigid in lock and key and non-rigid in induced fit In induced fit: the shapes of the enzyme, active site, and substrate adjust to maximumize the fit, which improves catalysis, there is a greater range of substrate specificity, Induced fit model is more consistent with a wider range of enzymes

What affects Enzyme activity:

Environmental conditions:

Max activity of enzyme= when all of the enzyme is binded to substrate

Cofactors and coenzymes:

•Inorganic substances (zinc, iron) and vitamins (respectively) are sometimes need for proper enzymatic activity. •Eg) Iron must be present in the quaternary structure - hemoglobin in order for it to pick up oxygen.

Inhibition:

Competitive:

Mixed inhibition:

Allosteric inhibitors-

V max= maximal velocity Km value= = ways you can tell if its competitive/non-competitive inhibition

Feedback inhibition:...