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56 Cards in this Set
- Front
- Back
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What is another name for D-Glucose?
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Aldohexose
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Hemiacetals are reversible/irreversible. Acetals and ketals are reversible/irreversible.
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Reversible; Irreversible
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At what pH does most life "go on?"
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7.4
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How is glucose changed to yield D-mannose?
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C2 epimer (axial)
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How is glucose changed to yield D-galactose.
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C4 epimer (axial)
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What is an aldose?
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An aldehyde-containing sugar.
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What is the empirical formula for a carbohydrate?
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(CH2O)n
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Why is intramolecular cyclization favored?
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Favored entropically
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What is glycosyl-B-1,4?
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Celluobiose
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What is glucosyl-alpha-1,4?
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Maltose
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What is repeated maltose called
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Glycogen; starch
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What is the difference in the open chain between glucose and fructose?
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In fructose, carbonyl is at C2 instead of C1.
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What is a furan?
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Furanose ring; cyclic 5-membered ring
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What is a pyran?
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Puranose ring; cyclic 6-membered ring
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What does enediolization of glucose do?
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Converts it from an aldohexose (with an aldehyde at one end) to a ketose (with a ketone)
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What is glucosyl-1,2-fructose?
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Sucrose
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Why is phosphate a reasonsbly good buffer?
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There will be a 9/1 rati of phosphate dianion to monoanion
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What does pKa indicate?
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The point at which a molecule is "okay with" maintaining a negative charge ~ lower pKa will be a better acid because it is willing to give away a proton
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What is the Keq driving force for cleavage of ATP to ADP?
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10^5
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What are kinases?
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Enzymes that carry out phosphoryl transfers
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What happens when Nu attacks the gamma P?
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Products are NuPO3^2- and ADP
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What happens when Nu attacks the alpha P?
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NuAMP and PPi
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What does Mg2+ do?
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Acts as a switch to cover the triphosphate sidechain charge (lowers electrostatic barrier so Nu can add)
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What are the 3 kinds of kinases?
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1. Galactokinase
2. Hexiokinase 3. Phosphofructokinase |
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What does galactokinase do?
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Transfers gammaP from ATP to C1 oxygen of a galactose hemiacetal form
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WHat does hexiokinase do?
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Phosphorylates glucose
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What does phosphofructokinase do?
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Adds P to C2 on fructose in addition to C6
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What is galactose metabolism?
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Simultaneous phosphoryl transferase (ATP) and nucleotidal transferase (UTP; attack at alpha)
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How are acetal beta linkages formed?
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Cellobiose synthase enzyme orients 4-OH of free glucose to attack.
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Does UDP add alpha or beta? Why?
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Alpha, because that way hexiokinase can have two interactions with water
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Why are sugars phosphorylated?
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To keep dianions inside cell and to activate oxygens as leaving groups
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What types of amino acids can act as bases/nucleophiles?
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Cys, His, Glu, Asp, Lys, and Tyr
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What are glycosides?
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Molecules containing sugar residues connected via C1 (acetal linkages)
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What are glycosidases?
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Enzymes that cleave glycosidases; Beta-glycosidases cleave beta-linked; alpha-glycosidases cleave alpha-linked
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What type of molecules serve as glycosidase inhibitors?
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Naturally occurring amine analogs, such as nojirimycin, with protonable amines at or near C1-oxygen; deoxynojirimycin is a powerful alpha glycosidase inhibitor; isofagamine is a powerful beta glyosidase inhibitor
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How do Serine proteases work?
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His = base catalysis; Ser-O- = nucleophile (nucleophilic catalyst)
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What does Phosphoglutamase do?
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Interconverts glucose-6-P & Glucose-1-P (which is what is released when broken down); it first adds phosphate to 1 position ~ glucose 1,6 P ~ transfer 6-P to dephosphorylated Ser (during this step, G-1,6-P must flip and Ser108P changes to Asp to prevent enzyme from becoming phosphorylated)
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What is allosteric inhibition?
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Binding to a distinct region of the active site or to a second site
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What percent of approved drugs are enzyme inhibitors?
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30%
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What is Vmax a measure of?
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How fast an enzyme is converting substrates to products
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What is the slope for the Lineweaver-Burk plot?
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Km/Vmax
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How do you calculate Km for competitive inhibition?
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Km,app = Km (1 + [I]/Ki)
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How do you calculate Km for noncompetitive inhibition?
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Km, app = Km
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How do you calculate Vmax for noncompetitive inhibition?
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Vmax,app = Vmax/(1 + [I]/Ki)
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How do you calculate Vmax for competitive inhibition
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Vmax,app = vmax
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How do you calculate v for a particular concentration of substrate?
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V = Vmax [S]/(Km + [S]) = kcat[s][Etot]/Km
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What is the relationship between Vmax, [Etot]. and [Kcat]
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Vmax = [Etot] Kcat
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How does AZT work?
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Serves as a competitive inhibitor by converting to AZTTP; azide group on AZTTP prevents polymerization
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What type of inhibitor is nevarapine?
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Noncompetitive
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How do statins work?
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Block the rate-limiting step in cholesterol synthase by competitive inhibition
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How does HMG Co-A reductase work?
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Changes 2 NADPH to NADP+ to catalyze 4-electron change of HMG CoA to melavonate
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What is Ki?
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Inhibition constant (50% inhibition)
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What range does Ki have to be in for the drug to be considered potent?
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nanomolar range
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What is the relation between Ki, Koff, and Kon?
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Ki = koff/kon
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How do you calculate half-life using Ki?
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Half-life = 0.69/Koff
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What statin has the greatest Ki and what has the lowest?
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Fluvastatin = greatest
Ruvastatin = lowest, because greatest number of bonding interactions (H-bond to Ser 656 increases affinity) |
