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Enzymes- reduce the amount of energy required for the reactions they catalyst [accelerate]. -thus, increasing the rate of reactions that occur in living organisms. enzymes : metabolism would be so slow at body temp. That insufficient energy would be available to sustain life. -Many enzymes are “Intracellular”- used within the cell that produced them e. G. Enzymes in respiration & photosynthesis -Others are “extracurricular”-they act outside the cells that produce them e. . Digestive enzymes -made of proteins, folded so they have a specific active site. -many enzymes also require a non-protein “cofactor”, in addition, to act, e. G. Metallic ions as: iron, copper, calcium, magnesium. -Co-enzyme: when the cofactor that acts with the enzyme to alter reaction rate, is an organic compound [e. G. Vitamin] Substrate: a compound act on by the enzyme Product: the compounds as a result of enzyme action.
Lock and key theory: the complementary fitting of an enzyme and substrate [like a Gig- saw] “Induced-fit” theory of enzyme action: when active site varies from substrate and the two only fit after contact when the substrate induces a complimentary shape at the active site of the enzyme. pH: an enzyme becomes less efficient if the variable value is greater or less than the optimal. -change from optimal can change an enzymes shape, affecting its ability to combine with its substrate = inability to act= decline in the rate of metabolic reactions.
Temperature: -most human enzymes optimal: 37 co [normal body temp] -HIGH temp= structure is permanently denatured [remaining inactive even when normal temp. Returns] -LOW temp= enzyme is inactive [however, active again when temp is normal] Enzyme Concentration: -if the mat. Of enzymes is increased the mat. Of product per unit of time increases, until no more substrate is available. – [Enzymes are avail. For reuse/ not used up per reaction] Substrate Concentration: -addition of more substrate to enzyme solution initially increases rate of reaction until all active sites are occupied of the set mat. F enzymes. E. G. All workers are busy. Inhibition: Competitive inhibition: whereby other molecules compete with the normal substrate for the enzymes active site. -permanent inhibition= death -Non- competitive inhibition: when non-competitive inhibitors bind to a site on an enzyme other than the active site, and change the enzymes D shape, in turn, the shape of he active site in another region. -substrate can still bind with usual affinity [attraction] but the enzyme no longer has the optimal arrangement to stabilize the transition state and catalyst the reaction.
Rational Drug Design: Construction of a drug to fit the active site of a molecule so that the natural action of the molecule cannot occur. -a technique in which the active site tot the molecule is determined and a second molecule [the drug] is constructed to fit into that active site to inhibit the activity of the first molecule. Denature: the modification of the molecular structure of a protein from its natural state.