Flashcards in Fundamentals Of Biochemical Rxns Deck (66):
A series of biochemical reactions
DeltaG = 0
DeltaG < 0
Spontaneous; exergonic/energy producing
DeltaG > 0
Non-spontaneous; endergonic/energy consuming
Keq = ?
Ratio of product to substrate
Keq dependent on concentration of products & reactants
Le Chatelier’s Principle
Most important type of reaction to preserve life
Normal body pH = ?
7.37 - 7.43
DeltaG’ = ?
When ATP breaks down into ADP + Pi, how much energy is released? (Same as thioester)
When ATP breaks down to AMP and PPi, how much energy is released?
When PPi is broken down, how much energy is produced?
Endergonic reaction coupled to exergonic reaction to make the former happen; must share a common intermediate
Coupled reactions (input of energy)
The first 3 steps of _____ are coupled and irreversible rxns controlled by mass action
Transfer of an atom to a multiple bond or elimination of an atom to form a multiple bond
Replacement of a functional group with another
Shifting of a functional group within a molecule
Transfer of an electron from one molecule to another
Involve molecules that donate protons (acids) and accept protons (bases)
Loses a proton
Gains a proton
The kidneys remove H+ from blood in the form of ____ and reabsorb HCO3-
Blood pH < 7.37
Hypoventilation leads to an increase in the concentration of CO2 in blood, called respiratory acidosis. This shifts the reaction to the:
Hyperventilation leads to a decrease in the concentration of CO2 in the blood. As a result, the reaction shifts to the:
How do enzymes increase reaction rate?
They lower the activation energy for the reaction
They DO NOT alter DeltaG
Transfer electrons from a donor (reducing agent) to an acceptor (oxidizing agent)
ex: lactate dehydrogenase
What are 6 examples of oxidoreductases?
Dehydrogenase, oxidases, peroxidases, reductases, monooxygenases, dioxygenases
Transfer a functional group between molecules
Add or remove atoms to or from a double bond
Form C-O, C-S, C-N, or C-C bonds with the hydrolysis of ATP
Cleave bonds via the addition of water
Substrate is a perfect fit for active site
Lock and key hypothesis
Binding induces conformational changes in active site
Induced fit hypothesis
Metal ions, essential trace elements, interact with enzyme via noncovalent interaction and stabilize the active site
Small organic molecules, derived from vitamins
Can be co-substrates or prosthetic
Cytochrome c oxidase, ferroxidase, superoxide disputable, lysyl oxidase, and tyrosinase all have ___ as a metal ion
Heme proteins cytochromes, catalases, and peroxidases all have ____ as a metal ion
ATPases, adenylate cyclase, and kinases all have ___ as a metal ion
Glutathione peroxidase uses ____ as a metal ion
Superoxide disputable, collagenase, alcohol dehydrogenase, alkaline phosphate, transcription factors, and carbonic anhydrase all have ____ as a metal ion
This protein requires both Copper (Cu) and Zinc (Zn)
Superoxide dismutase (antioxidant): binds the free radical of molecular oxygen
Ex: NAD+ ..loosely associated, leaves in a changed form (NADH, reduced; also reverse)
Permanent association; almost a part of the enzyme
Ex: FAD, FMN, heme
What is the ideal temp for enzymes?
37 degrees C
What is the ideal pH for enzymes?
EXCEPT gastric enzymes such as pepsin
Phosphorylation and dephosphorylation are both examples of:
Pumps H+ into lumen where it combines with Cl- to form HCl
Found in parietal cells lining gastric lumen
Proton pump inhibitors may cause
Resemble substrate; compete with substrate binding by binding to active site; can be overcome by increasing the substrate concentration
Binds to E and ES (enzyme-substrate intermediate) at site other than substrate binding site
Only binds to ES complex; site other than substrate binding site
In competitive inhibition, what happens to Vmax and Km?
There is no effect on Vmax
Km increases (decreased affinity because the active site is blocked)
There is also a larger substrate concentration needed to achieve 1/2Vmax
In non-competitive inhibition, what happens to Vmax and Km?
Vmax decreases because the reaction is not proceeding
Km is unchanged because the active site is still available
In uncompetitive inhibition, whaat happens to Vmax and Km?
Vmax and Km decrease by the same factor
How are metalloenzymes inhibited?
The cofactors (like Mg2+ and Zn2+) are chelated
Chelating agent ex: ethylene diamine tetraacetic acid (EDTA)
Describe chelating agents for lead poisoning
Lead is involved in heme biosynthesis....heme is a conenzyme for hemoglobin. Lead poisoning is treated by administering EDTA-CA with dimercoprol; lead has a higher affinity for EDTA than Ca does, so it displaces it and binds to the EDTA. Then, this is excreted out
Destruction or covalent modification of the key functional groups of amino acids in an enzyme; irreversible loss of function
In enzyme inactivation, what happens to Vmax and Km?
There is a decrease in Vmax
Km is unchanged
THIS IS THE SAME AS NON-COMPETITIVE INHIBITION
Activity modulated by noncovalent binding of a metabolite to a site other than the catalytic site; affects substrate binding by inducing conformational changes
Usually r/t the first reaction or rate limiting step
Last product usually negative effector; “feedback inhibition”
Same catalytic function, different primary sequence
Include markers of MI such as CK-MB, AST, LDH-1, although these are nonspecific
A protein complex which is pertinent to heart muscle contraction
Ca2+ binding causes a conformational change, transmitted to tropomyosin, allowing myosin to bind to actin filaments —> muscle contraction
Max sensitivity 10-24 hours after onset of acute MI