Enzymes + Anticancer Cancer Drugs
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Role of enzymes as catalysts?
They increase the rate of reactions by lowering thr avtivation energy
What type of interactions occur between an enzyme active site and a substrate?
Ionic bonds, hydrogen bonds and van der Waals forces
What type of bonding allows enzymes to bind to substrates?
Intermolecular forces
What happens to the active site when a substrate binds? (actve. ste. chngs. shp. - bcme. cmplmntry. sbstr. - indcd. fit)
Active site changes shape to become complementary to the substrate, induced fit
What effect does enzyme binding have on the substrate? (bnds. sbstr. brkn. + nw. bnds. may frm. lwrng. actvtn. E )
Bonds in the substrate are broken and new bonds may form lowering the activation energy
What does it mean that enzymes are stereospecific?
They only catalyse reactions for one specific optical isomers
Why are enzymes stereospecific?
The active site has a specific 3D shape that only fits one enantiomer
Why is designing enzyme inhibitors difficult?
Enzymes are stereospecific and different enantiomers of inhibitors may interact differently with enzymes
What is an enzyme inhibitor?
A molecule that blocks the active site and prevent substrate binding
Draw cisplatin
How does cisplatin bind to DNA?
Forms a bond between platinum and nitrogen atoms on guanine Occurs via ligand replacement
Explain why cisplatin prevent DNA replication? (C undrgs. lgnd. sub. frmng. bnds. btwn. pltm. + N atms. Ganne. DNA, cses. crs. lnkng. wthn. DNA. dstrts. strctr. + prvnts. frm. unclng. DNA. rplctn. cnt. ocr.)
Cisplatin undergoes ligand substitution, forming bonds between the platinum ion and nitrogen atoms on guanine in DNA. This causes cross - linking within the DNA, which distorts its structure and prevents its from uncoiling, so DNA replication cannot occur
What is the effect of cisplatin on cancer cells?
Prevents DNA replication, so cells cannot divide
Why can cisplatin have adverse effects?
Affects both cancerous and healthy cells, especially fast-dividing healthy cells