Kine 324 exam 1

enzyme synthesis

(copy) transcriptional control: gene expression limiting pretransitional control: limitation at ribosome amino acid-->enzyme protein

redox potential

-a measure of electrical driving force -the tendency for electrons to move in a particular direction -oxidation-reduction potential (redox potential) is analogous to chemical Keq values -a driving force exists between the fuel electrons and oxygen -carbohydrate and fat are highly reduced (electron rich) -oxygen is electron poor -oxygen readily accepts the electrons from fuels -energy released as the electrons go down the electrical (redox) prudent is used to synthesize ATP -redox potential can be quantified in the lab

laws of thermodynamics

E in=E out (work) + E (heat) +/- E stored (fat)

equilibrium constant (Keq)

Keq is a measure of the tendency of a rxn to proceed. the greater the Keq, the greater the "chemical pressure" of the rxn Keq=products/reactants more negative Keq, more likely rxn to occur

enzyme regulation

catalytic does the work. cant work closed, add phosphate through kinase to open up catalytic to do work. phosphotase takes phosphate. -hexokinase: muscle -glucokinase: liver

2 basic mechanisms to regulate enzyme activity

chronic- enzyme amount: train to get more enzyme to work more quickly acute-catalytic efficiency Q10 of an enzyme=factor by which the Vmax of an enzyme changes for every 10*C change in temp ex: Q10= 20 when increasing T from 25-35*C will double Vmax

enzyme inhibition

competing for same binding site. more ethanol competing that methanol

regulation of enzyme amount

constitutive enzymes inducible enzymes

strong bonds

covalent bonds- shared electrons -peptide- responsible for 1 structure -disulfide- formed by 2 residues, 2 structure

first order rxn are

dependent on substrate concentration

ATP supply vs ATP demand

dependent upon -coordination of fuel type -utilization -fiber type recruitment -regulation of ATP demand: cell will not let itself run out of ATP

^Eh

driving force for electrons to move down the electron transport chain -NADH releases 2 electrons to become NAD+ and the 2 electrons turn 1/2 O2 into H2O

thermodynamics

energy change: ^E entropy change: T^S (disorder) enthalpy: ^H (heat) free energy: ^G (energy free to do work)

^G= -nF^Eh

energy made available when electrons go down an electrical gradient is given by the product of: the size of the electrical gradient(^Eh) the number of electrons going down the gradient(n) and a proportionality constant (F) to express the energy made available in calories

exergonic rxns liberate

energy while endergonic rxns require energy input

heat and temp mechanical application

engines use the heat to convert to mechanical energy

enzyme activity depends on

enzyme amount catalytic efficiency

enzymes reduce activation energy

enzyme catalysis reduces the activation energy of a rxn ^G of rxn is not affected by catalysis path of rxn is changed by catalysis, but not initial and final states

open thermodynamic system

exchange both matter and energy equilibrium thermodynamics do not apply -flow of matter and energy across boundaries precludes attainment to true equilibrium

structural protein

fibrous proteins. operates like the structural element of cells instead of acting like and enzyme

disulfide bond

formed when 2 polypeptide chains are covalently linked by cystine side chains (R groups)

reversible rxn

forward rate v=k1[A] backward rate v=k-1[B]

enzyme degradation

gene-->protein enzyme protein-->amino acids a specific enzyme changes the structure of the neurotransmitter so it is not recognized by the receptor. For example, acetylcholinesterase is the enzyme that breaks acetylcholine into choline and acetate.

exergonic rxns

gives up energy activation energy

energetic equivalent per L O2

glucose has more energy per L of O2

heat and temp biological application

heat is a useless byproduct

modulation by effectors

hexokinase by glucophosphate short term, positive or negative regulation w/n given metabolic pathway between 2 pathways product inhibition: citrate inhibits citrus kinase freeforward regulation

weak bonds

hydrogen-responsible for 2, 3, and 4 structure hydrophobic- formed by nonpolar side chains, assist in 3 structure electrostatic- salt bonds formed by ionized R group, 4 structure

energy systems contribution over time

immediate: immediate high contribution lasting very little time nonoxidative: high contribution lasting fair amount of time oxidative:beginning low contribution works to high and stays high overtime

^Eh is

index of electron affinity

Q10 effect

is a measure of the temperature dependence of enzyme activity

Gibbs free energy

isolated system: driving force for a rxn is an increase in S magnitude of driving force for rxn is given by: ^G=-T^S

enzymes

large biological molecules responsible for thousands of metabolic processes sustaining life. highly selective catalysts. greatly accelerate rate and specificity of metabolic reactions

inducible enzyme

levels fluctuate according to environmental demand, i.e. alcohol dehydrogenase as you ingest alcohol, enzymes are built high energy expense for body to maintain high levels of enzymes training: mitochondria, don't use it ya lose it, same for enzymes

catalytic site

location on enzyme where substrates bind and chemical transformation occurs

^G=^H-T^S

magnitude of ^G is a measure of the 'push' of the rxn

constitutive enzyme

maintained at relatively stable levels not responsive to environmental stimuli, i.e. exercise training

ATP utilization end

mechanisms to protect against degradation of energy homeostasis

ATP production end

metabolic source muscle fiber recruitment (small-large) nonoxidative vs oxidative muscle fiber recruitment small=oxidative 1st recruited don't want to break down fat w/o being able to use it fuel must be appropriately integrated

catalyst

molecule that participates in and undergoes physical change then reverts to original form when rxn is complete -organic molecules are highly unreactive

lipid stores

more energy per unit mass while carbohydrate yields more energy per L O2 consumed

energy metabolism

must be matched

isolated thermodynamic system

no exchange of either matter or energy with surroundings thermodynamically represent a micro universe ex: ideally insulated thermos bottle

closed thermodynamic system

no exchange of matter energy is exchanged ex: hot water bottle

rxn rate depends

on frequency and energy collisions

kinase

phosphorolates adds phosphate

covalent modification

phosphrylation long term, positive or negative

modulators

positive or negative internal -often products of the pathways, typically negative external -often products f the pathways or hormones

catalytic efficiency is

positively and negatively affected -covalent modificatin, product inhibition -modulated rxnz/steps are early in metabolic pathways

protein structure

primary structure(1) -amino acid sequence secondary structure (2) -shape of the amino acid sequence tertiary structure(3) -folding of single polypeptide chain quaternary structure (4) -2 or more polypeptide chains united by weak bonds

free energy related to Keq

products/reactants

complex protein

protein containing a simple protein and at least one molecule of another substance

first order rxn

rate is linerly dependent on S -rate= k[A] k is rate constant

critical importance to energy metabolism

rate of ATP production must precisely match ATP utilization

rxn rate of enzyme-catalyzed rxn

rate of product formation (rate of run) given by: v=k2[ES] problem: we can't know k2 of [ES] solution:Km=(k-1+k2)/k1 v=velocity result:mechaelis-menton equation v=(Vmax[S])/(Km+S)

kinetic theory of rxn

rate of rxn depends on: frequency of collisions energy of collusions (to overcome energy of activation)

phosphotase

removes phosphate

endergonic rxn

requires energy

lohmann reaction

reversible rxn, catalysed by creatin kinase, in which ATP and creatine are formed from ADP and phosphocreatine

^G=0

rxn is at equilibrium

zero order rxn

rxn rate is independent of substrate independent of A

^G>0

rxn will not proceed spontaneously

^G<0

rxn will proceed spontaneously

transport protein

serves function of moving other materials within an organism

allosteric sites

sites on the enzyme where specific molecules may bind resulting in a modification of the change in the catalytic efficiency

properties of enzymes

specificity: an enzyme catalyzes only one reaction coenzymes -nonprotein organic molecules -holoenzyme= apoenzyme + coenzyme -bound covalently or noncovalently -NAD, FAD, TPP, Pyridoxal phosphate -are co-substrates

bioenergetics

study of energy transfer in biology energetics=thermodynamics

michaelis-menton kinetics demonstrate

substrate dependence, as well as saturation -Vmax is the maximum velocity of a run -Km indicates the affinity of an enzyme for a substrate

flux generating step

substrate saturated ([S]>>Km) origin of carbon flow, but not necessarily rate-controlling can be glycogen or glucose

enzyme amount depends on

synthesis and degradation (turnover of proteins) -transcriptional control

basic structure of thermodynamics

system= compartment under consideration surroundings=everything outside of system system+surroundings=universe only concerned with energy change(^E or ^H)

reduction

the addition of electrons

oxidation

the removal of an electron

hydrogen bonds

the sharing of an H atom between N and carbonyl oxygen of different peptide bonds in the same or different peptide chains

Actual redox potential, ^Eh, of a redox couple

-actual redox potential must take into account the concentrations of reduced and oxidized species -actual redox potential at pH 7: Eh= Em + (2.3RT/nF) log(ox/red) Em:midpoint F: faraday constant= 23.062 n= # e- transferred

usefulness of bioenergetics

-calculation of the energy change allows quantification of useful work that can be done -calculation of thermodynamics efficiency -id of allowable vs impossible rxnx/mechs/stoichiometries -gluconeogenesis via the reversal of the pyruvate kinase reaction -stoichiometry of ATP production/fuel utilization -nonequilibrium (irreversible) thermodynamics -allow calcs of rate of energy flow

1st law of thermodynamics

-conservation of energy in the universe -forms of energy can be transducer -chemical=ATP, food -electrical=neurons -mechanical=muscle -thermal=heat generation -energy transduction has quantitative correspondence -mechanical eqivalent of heat is 4.18 J/cal -heat changes and chemical runs -heat evolved in run establishes upper limit to the amount of work the rxn can perform -heat is easily measured -standard conditions -25*C -1 atm -pH 7.0

remember 1st law of thermodynamics

-energy is neither created nor destroyed -energy may be transduced

catalytic and allosteric sites of enzymes

-formed by tertiary and or quaternary structure

^G

-probability of a rxn to occur -different forms of ^G -can be calculated from the ratios of products and reactants -^G can be calculated from ^Eh -differnet forms of ^G inter-related -change in one form affects value in other form

general order of rxn

A--->B

^Eh is potential diff between 2 redox couples

^Eh= Eh(e- acceptor) - Eh(e-donor)

different forms of ^G

^G itself: -available energy change in chem runs -ex: energy changes in -rxns of glycolytic pathway -hydrolysis/synthesis of ATP (^G ATP) ^E-redox potential change -available energy changes in runs involving the transfer of electrons -ex: energy changes in -electron transfer rxns of electron transport chain ^u- electrochemical potential of an ion across a gradient -available energy change in the flux of an ion across a gradient -ex: energy changes in -Ca2+ flux across the SR membrane -proton flux across the inner mitochondrial membrane

calculating actual ^G'

^G'=^G*'+2.3RT log r

standard free energy (^G*') and Keq

^G*'= -RT ln Keq ^G*'= -(2.3)RT log Keq R=1.987 cal/deg mol

each energy system has

a different capacity and rate of ATP production fastest is creatine phosphate

simple protein

a protein that only yields amino acids when hydrolyzed

catalysis

acceleration of chemical reactions

enzymes reduce

activation energy

Michaelis constant

affinity enzyme has for a substrate Km Km is concentration of S at 1/2 the max enzyme velocity STUDY SLIDE

catalytic efficiency

amount of substrate