Metabolism_Intro.csv

anabolism is energy-requiring while catabolism releases energy; anabolism is diverging while catabolism is converging; anabolism results in complex molecules while catabolism results in simple molecules

oxidation-reduction (involves electron transfer); ligation requiring ATP cleavage (results in formation of C-C bonds); isomerization (results in rearrangement of atoms); group transfer (results in transfer from one functional group to another); hydrolytic (involves cleavage by water); addition or removal of functional groups (involves breaking or creation of double bonds)

irreversible under physiological conditions; have a committed step - must continue down pathway (usually = rate-limiting step); regulated (especially at rate-limiting step & branch points); compartmentalized

isoforms; substrate concentrations; product inhibition; allosteric regulation; covalent modification; changes in enzyme protein concentration (induction & repression & sequestration & degradation)

varies between 0 (only AMP) and 1 (only ATP); equal to ([ATP]+ 0.5[ADP])/([ATP]+[ADP]+[AMP]); high energy charge -> increase in anabolic reactions and decrease in catabolic reactions

determination of level of metabolites in blood (esp. glucose & cholesterol & triglycerides); release of enzymes into bloodstream following tissue necrosis in disease state; ELISA (link immunology with enzymology - Ab coupled to enzyme -> colorimetric assay); enzymes can be targeted by poisons

enzymes are usually protein and catalyze reactions without being used up; coenzymes are small molecules or metals that combine with apoenzymes (proteins) to form a functional enzyme; coenzymes and apoenzymes cannot function as enzymes on their own

hyperbolic curve representing rate of rxn vs. substrate concentration; Vo = Vmax[S]/(Km + S); [S] = substrate concentration; Vmax represents rate of catalysis and enzyme concentration (large Vmax -> high reaction speed); Km reflects enzyme affinity for substrate (large Km -> low affinity)

Vmax = reaction rate (depends on amount of enzyme [Et]); Kcat = turnover number = number of units of substrate molecule each enzyme molecule converts to product per unit time = Vmax/[Et]; unit of enzyme activity = micromoles of product formed/minute; specific activity = units/mg protein = enzyme activity per mg of total protein = measure of enzyme processivity at a certain level of substrate

oxidoreductases; transferases; hydrolases; lyases; isomerases; mutases; ligases

catalyze oxidation-reduction reactions - include dehydrogenases (remove hydrogen); oxidases (oxidation-reduction involving oxygen as the electron acceptor); reductases (catalyze reductions); peroxidases (reduce hydrogen peroxide & other peroxides); catalase (catalyze decomposition of hydrogen peroxide to hydrogen and water); oxygenases (catalyzes the incorporation of an oxygen into a substrate); hydroxylases (catalyzes the addition of -OH groups)

transfer functional groups between donors and acceptors; examples: kinases (transfer phospho groups); phosphomutases (transfer phosphate esters from one OH group on a substrate molecule to another OH group on the same molecule)

catalyze cleavage of bonds through the addition of water; include proteases (hydrolyze amide bonds in proteins); lipases (hydrolyze ester bonds in lipids); phosphatases (hydrolyze phosphoester bonds)

add or remove elements such as water/ammonia/carbon dioxide to/from a substrate molecule; include decarboxylases and dehydratases such as fumerate and malate

"heterogeneous; catalyze inversions at asymmetric carbons (ie

heterogeneous; catalyze intramolecular transfer of groups such as phosphates from one site to another site within the molecule

catalyze the joining of two molecules using energy derived from ATP; also called synthetases

creatine phosphokinase (peaks around 24h after MI); lactate dehydrogenase (peaks around 36040h after MI); aspartate aminotransferase; gamma glutamyl transferase

acetylcholinesterase inhibited by organophosphates (pesticides/nerve gases); cyclooxygenase 1 & 2 modified by aspirin