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Flashcards

Enzymes

Adrianna Bialecka Med Chem and Chem Bio University Inglês 49 flashcards

Enzymes

Flashcards do conjunto (49)

  1. 1What are enzymes?Enzymes are the catalysts used to accelerate organic reactions in living organisms. They are large protein molecules, containing molecules, containing hundreds of amino acids. As catalysts they have many attractive features such as the ability to catalyse a wide variety of reactions, under very mild conditions, with very high efficiency and selectivity
  2. 2How are enzymes complex organic/organometallic catalysts?-they can be used in the laboratory much like conventional catalysts.
    -They can be isolated from cells and used in purified form, and hundreds are commercially available
  3. 3What is fermentation?The use of microorganisms to produce useful product in bulk, taking advantage of their natural biochemical pathways. Currently many important compounds are produced commercially in this way e.g. lactic acid, amino acids and penicillins
  4. 4How is genetic engineering used to produce new strains of microorganisms?-These organisms have had some genes added or removed, so that the production of certain enzymes is enhanced or reduced, and the biochemical pathways are altered to provide compounds which are not in viable quantities from natural organisms
  5. 5What are the advantages of enzyme catalysts?->Enzymes can be very efficient catalysts
    -the huge rate enhancements they provide make it possible to carry out reactions at reasonable rates under exceptionally mild conditions- usually near room temp, in water, at near neutral pH. This means that sensitive compounds can be prepared, engineering costs are usually low, and the processes are more environmentally friendly [RATE accelerations of 10^9 to 10^12 are common]
    ->Enzymes catalyse many types of chemical transformations
    Enzymes catalyse most types of chemical reactions, including some transformations which are difficult or impossible to achieve using conventional methods. Hundreds of enzyme are available commercially and thousand of strains of microorganisms can be screened, so it is often possible to get the desired reactivity
    ->Enzymes are highly selective catalysts
    They are selective in two distinct senses. First, they often show high substrate specificity, i.e. they only catalyse the reaction of a very limited range of substrates. This can be a disadvantage, but it is fair to say that enzymes are no less variable
  6. 6What are the characteristics of enzymes?Enantiomerically pure. One enantiomer of a substrate can usually fit into the active site much better than the other
    -Second, enzymatic reactions are usually highly chemoselective, regioselective and stereoselective. They usually interact with substrates in such a way that the product is formed in a highly enantioselective manner. Only a handful of conventional catalysts systems provide such high enantioselectivity, and for many very important reactions there are no competitors
  7. 7Example of enzyme catalysed reactions?A) Production of amino acids by kinetic resolution
    -Amino acids are very important both in their own right and as precursors for a wide variety of other compounds. Many are produced on a multi-thousand ton scale each year. Some are synthesised in the lab, and some are isolated by various microorganisms
    -A more recent approach is the use of enzyme-catalysed chemical reactions. Several aa;s are industrially produced using this process. It starts from aa's which are readily prepared by chemical synthesis, in racemic form, i.e. as a 50:50 mixture of the two enantiomers
  8. 8Production of amino acids by kinetic resolution exampleIt was hoped that enzymes that hydrolysed peptide bonds might be used to hydrolyse the amides stereoselectively. A strain of pseudomonas putida was found to hydrolyse a variety of amides. The L-amides were hydrolysed highly selectively, and the reaction could be stopped at 50% conversion to give a mixture of L-amino acids and unreacted D-amino amidesProduction of amino acids by kinetic resolution example
  9. 9—
  10. 10What is Aspartame?It is a simple dipeptide, which is manufactured on a thousand ton scale for use as a synthetic sweetener. One production method relies on an enzymatic process developed by Tosoh Corporation of Japan. It involves dipeptide formation between N-protected L-aspartic acid and racemic phenylalanine methyl ester catalysed by an enzyme called thermolysin
  11. 11How is Aspartame produced?How is Aspartame produced?
  12. 12What were the noteworthy features of the production of aspartame reaction?-Best results obtained with a thermolysin from a bacterial strain that was isolated from hot springs, and isolated enzyme shows optimum activity at 50-60 degree Celsius.
    -The reaction is the reverse of the natural reaction catalysed by the enzyme, under the aqueous conditions the equilibrium normally strongly favours hydrolysis, not amide formation. However the reaction is driven by precipitation of a complex between the product and the unreacted D-phenylalanine ester. This is an example of separation of enantiomers (resolution) by taking advantage of the faster reaction of one of them- it is a kinetic solution
    -The reaction conditions are very mild: water, pH = 7. There is an enormous rate acceleration- this is an extremely slow transformation in the absence of a catalyst
    -There is no hydrolysis of the ester or the protecting group i.e.
  13. 13What are the disadvantage of enzyme catalysts?-High cost, poor stability
    -Water is not an ideal solvent
    -Some enzymes require cofactors
    -Selectivity problems
    -Not many enzyme catalyzed C-C bond forming reactions
  14. 14What are nucleic acids?they are biological molecules that encode genetic information
  15. 15What is DNA?deoxyribonucleic acid
  16. 16What is RNA?ribonucleic acid
  17. 17What is the general structure of nucleic acids?-Nucleic acids consists of four kind of bases linked to a sugar-phosphate backbone. RNA and DNA differ in the sugar component and one of the basesWhat is the general structure of nucleic acids?
  18. 18What are the different bases of DNA and RNA?4 different bases but one of these is not shared, which means we have a total of 5 structures
    -2 purine derivatives and 3 pyrimidine derivatives
    -Every base derives from one of the following two molecules    What are the different bases of DNA and RNA?
  19. 19What are the 5 different base structures?What are the 5 different base structures?
  20. 20What sugar does DNA have?DeoxyriboseWhat sugar does DNA have?
  21. 21What sugar does RNA have?riboseWhat sugar does RNA have?
  22. 22How is the phosphate link?-The phosphate links the C5' of one (deoxy)ribose with the C3' of the next one [Phosphodiester bond]
    -Monomeric structure of DNA/RNA is in fact a 3 piece molecules known as a nucleotide    How is the phosphate link?
  23. 23What is the full structure of a nucleotide?What is the full structure of a nucleotide?
  24. 24What are anomeric carbons?-the anomeric carbon is the one that has a base attached to it, C1
    -If the Anomeric carbon's hydroxy group is trans to the CH2OH group, then the sugar is an alpha anomer
    -If the Anomeric carbon's hydroxy group is cis to the CH2OH group, the sugar is a beta anomer    What are anomeric carbons?
  25. 25What is a N-glycosidic bond?-When the anomeric carbon is bound to some other group via a nitrogen atom, like in nucleotides, we refer to that bond as an N-glycosidic bond
    -Although the glycosidic bond can be either alpha or beta in nucleotides there is only the formation of the beta anomer
  26. 26What are nucleosides?What are nucleosides?
  27. 27What are the different types of adenosines based on phosphate amount?What are the different types of adenosines based on phosphate amount?
  28. 28How are DNA and RNA nucleotides linked together to one another?linked via phosphodiester bond (always C5' to C3').
    A phosphodiester bond is a group of strong covalent bonds between the phosphorus atom in a phosphate group and two other molecules over two ester bonds    How are DNA and RNA nucleotides linked together to one another?
  29. 29What does kinase do?What does kinase do?
  30. 30What are the steps involved in nucleotide joining?What are the steps involved in nucleotide joining?
  31. 31What aids the polynucleotide biosynthesis?the nucleotides are linked to one another enzymatically (DNA or RNA polymerases). The enzyme selects the right nucleotide and elongates the chain
  32. 32What is the structure of DNA?molecules is made up of two strands wound around each other to form a double helix
    -The green and yellow lines are the nitrogenous bases, the red pentagons are the sugar backbone
    -RNA is almost always a single-stranded molecule
  33. 33What is the structure of the Double Helix?What is the structure of the Double Helix?
  34. 34What attaches adenine-thymine base pair?What attaches adenine-thymine base pair?
  35. 35What attaches guanine-cytosine base pair?What attaches guanine-cytosine base pair?
  36. 36What is a hydrogen bond?It is formed when the negative end of one molecules becomes oriented to and semi-attached to the positive end of another. Hydrogen bonds are fairly weak, but many of them in series as seen in DNA can be quite strongWhat is a hydrogen bond?
  37. 37What are the bond lengths of different bonds?What are the bond lengths of different bonds?
  38. 38What is the function of nucleic acids?1. to transfer genetic information (replication and transcription)
    2. To synthesis enzyme and other proteins (translation)
    -During cell division the genetic information must be retained in the daughter cells
  39. 39When a cell divides where does the extra DNA come from?An exact copy of the DNA must be created prior to cell division
    -Any errors represent genetic mutations
  40. 40How does DNA replication happen?How does DNA replication happen?
  41. 41What does DNA have?all the information required to synthesise proteins
  42. 42What are the two steps that biosynthesis of proteins require?The transcription process (from DNA to mRNA) and the translation process in which the mRNA sequence is converted into a chain of amino acids
  43. 43What is transcription?-DNA unwinds and the RNA polymerase binds to the promoter region initiating the mRNA synthesis (5' -> 3')
    -The transcription continues until the entire gene has been converted to RNA    What is transcription?
  44. 44What is translation?-The mRNA may undergo modifications (elongation or capping, removal of introns) before being transported into the cytoplasm
    -tRNA is produced by DNA as needed
    -The tRNA carries a specific amino acid linked to the 3' end of the polynucleotide. The charged tRNA is made by aminoacyl tRNA-synthetase enzymes- ATP dependent    What is translation?
  45. 45What type of bond do you expect between an amino acid and the nucleotide?What type of bond do you expect between an amino acid and the nucleotide?
  46. 46Reaction mechanism for Aminoacyl tRNA-synthetase reactionReaction mechanism for Aminoacyl tRNA-synthetase reaction
  47. 47How does translation work?How does translation work?
  48. 48What bond forms between two amino acids?What bond forms between two amino acids?
  49. 49—

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University Med Chem and Chem Bio (Amino Acids) FlashCards sobre Enzymes, criado por Adrianna Bialecka em 10-02-2025.
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