enzyme catalysis control

allos enz that cat condensation of aspartate and carbamoyl phosphate to N-carbomoylaspartate

• final prod of pyrimidine biosynth
• feedback inhibitor of ATCase; binds to allos site of ATCase

cat act; not affected by CTP; trimer; 6 active sites

no cat act; binds CTP, dimer

N-(phosphonaacetyl)-L-aspartate: bisubstrate analog of ATCase; can show active site of ATCase

relaxed state; high aff for substrate; capable of binding substrate and is fully active

tense state: inactive and low aff for substrate

display sigmoidal shape invece perche' the transition from inactive T state to active R state w/ increase in subst conc. Subst binding in one site will increase enz act of remaining sites....cooperativity

OR: sigmoidal curve is composite of two Michaelis-Menton curves; one for T state and one for R state; at low conc of subst, enz inactive form and resemble T state but as subst conc increase, enz goes to R state. Combining two curves gives an int which is sigmoidal

stabilizes inactive T state; now harder for enz to go to R state

allos act of ATCase; binds to same site as CTP, but stabilizes R state, increases subst aff, and increases act

binding of a small molecule effects binding of some other chemically distinct mol

binding a sm mol affects binding of other sm mol of same type (i.e. subst)

all or none model; no combo of R and T states; subunits are either ALL in R state or ALL in T state

binding one subst mol converts all other subunits to R state--->only positive cooperativity is poss; if one subunit loses a mol then others will NOT lose their mol

enz can have any combo of R and T states simultaneously; conf change in one subunit may increase of decrease aff of other subunits--->allows for BOTH pos and neg cooperativity

high ATP means there are a lot of purines in the env, therefore more pyrimidines need to be made to balance out; final end prod of ATCase is CTP which is used in pyrimidine synth--->overall: high ATP stim ATCase act to make more CTP

diff enz that cat same rxn; can differ in struct, kinetics, and regulatory prop; allow for fine-tuning of rxns

• 2 forms: M and H
• tetramer

(M) subunit of LDH; M4 func in anaerobic env

(H) subunit of LDH; H4 func in aerobic env (aka heart); allos inhib by pyruvate

remember properties of M4 and H4 (M4 is anaerobic and H4 is aerobic); if there is an imbalance of M:H then there is something wrong

per esempio: if there is more H4 than H3M in blood, then indication of myocardial infarction bc H4 has gotten out of heart (aerobic) into anaerobic env

reversible attachment of donor molecules that affect enz func; can shift equil of active and inactive states

• donor: ATP
• ex prot: glycogen phosphorylase
• func: gluc homeostasis; E transduction

• donor: acetyl CoA
• ex prot: histones
• funct: DNA packaging, transC

• donor: myristoyl CoA
• ex prot: Src
• func: STP

• donor: NAD
• ex prot: RNA pol
• func: transC

• donor: farnesyl pyrophosphate
• ex prot: Ras
• func: STP

• donor: HCO-3
• ex pro: thrombin
• func: blood clotting

• donor: 3'-phosphoadenosine-5'-phosphosulfate
• ex prot: fibrinogen
• func: blood-clot formation

• donor: ubiquitin
• ex prot: cyclin
• func: control of cell cycle

enz that cat phosphorylation of prot by transferring gamma (terminal) phosphate group of ATP to OH groups of Ser, Thr, Tyr on targets

cat de-phosphorylation of proteins

• Ser/Thr kinase
• act by cyclic nucleotides

• Ser/Thr kinase
• act by cyclic nucleotides

• Ser/Thr kinase
• act by Ca2+ and calmodulin

• Ser/Thr kinase
• act by Ca2+ and calmodulin

• Ser/Thr kinase
• act by AMP

• Ser/Thr kinase
• act by diacylglycerol

• autoinhibited form is NOT phosphorylated
• phosphorylation of activation loop (Tyr 412) causes allosteric stabilization of R state

conversion of inactive enz into act one via proteolysis

inactive precursors; act by cleavage of one or a few peptide bonds; irreversible