PROTEINS: Study Guide Flashcards
What is the definition of side chain and simple protein
Sidechain: a group of atoms attached to the main part of a molecule and having a ring or chain structure.
Simple Protein: protein that yields only alpha-amino acids or their derivatives by hydrolysis; e.g., albumins, globulins, glutelins, prolamines, albuminoids, histones, protamines.
What is the definition of a conformational isomer?
Any of two or more isomers that differ only in stereochemical configuration. They have the same chemical formula but differ in spatial arrangement.
What is the difference between Protonation and Deprotonation?
Protonation: The addition of a proton (hydrogen ion) to an atom, molecule or ion, normally to generate a cation.
Deprotonation: is the removal (transfer) of a proton (or hydron, or hydrogen cation), (H+) from a Brønsted–Lowry acid in an acid–base reaction. The species formed is the conjugate base of that acid.
What is the difference between acidic and basic AA
Acidic: polar and negatively charged at physiological pH. Both acidic amino acids have a second carboxyl group.
Basic: Basic amino acids are polar amino acids that have a positive charge at the neutral pH.
what is the definition of proteinogenic?
amino acids that are incorporated biosynthetically into proteins during translation. The word “proteinogenic” means “protein creating”.
what is the definition of a salt bridge?
an interaction between two groups of opposite charge in which at least one pair of heavy atoms is within hydrogen bonding distance. Salt bridges can contribute to protein stability, although the effect depends on the environment
what is the definition of an Isoelectric point
the pH at which a particular molecule carries no net electrical charge.
what is the definition of a disulfide bond?
also called an S-S bond, or disulfide bridge, is a covalent bond derived from two thiol groups.
what is the definition of pKa
Therefore, the pKa is a quantitative measure of how easily or how readily the acid gives up its proton [H+] in solution and thus a measure of the “strength” of the acid. Strong acids have a small pKa, weak acids have a larger pKa.
What is the difference between monomorphic and polymorphic
Polymorphism: as related to genomics, refers to the presence of two or more variant forms of a specific DNA sequence that can occur among different individuals or populations. (common variant)
monomorphic: Having but a single form; retaining the same form throughout the various stages of development; of the same or of an essentially similar type of structure;
What is the difference between a beta-turn and helix loop
beta turn: generally occur when the protein chain needs to change direction in order to connect two other elements of secondary structure. The most common is the beta turn, in which the change of direction is executed in the space of four residues.
helix loop: s a protein structural motif that characterizes one of the largest families of dimerizing transcription factors.
what is the difference between glycoprotein and proteolipid
glycoprotein: proteins containing glycans attached to amino acid side chains. Glycans are oligosaccharide chains; which are saccharide polymers, that can attach to either lipids (glycolipids) or amino acids (glycoproteins).
proteolipid: a protein covalently linked to lipid molecules, which can be fatty acids, isoprenoids or sterols.
what is the definition of hydrophobic interaction
the tendency of nonpolar groups or molecules to aggregate in water solution.
what is the definition of the native state
the native state of a protein is it’s properly folded and assembled form with operative structure and function. The native state of a protein needs all four levels of biomolecular structure
what is the definition of the subunit
a protein subunit or subunit protein is a single protein molecule that assembles (or “coassembles”) with other protein molecules to form a multimeric or oligomeric protein
P1: Know the major elements required for life present in all amino acids (AAs).
carbon, oxygen, hydrogen (CHNOPS)
P1: Proteins are considered to be “true polymers”. Why?
- large molecules composed of many repeating monomers (interlinked)
-proteins are polymers comprised of amino acids (monomers)
P1:Be able to identify the alpha carbon within the general structure of a free AA.
- general structure: central alpha carbon, primary/ alpha carboxyl group, side chain, primary amine and hydrogen
-find the amine group connected to the carboxyl- it will be the carbon that they share/ connect with
P1:Know the four groups of AA. Which ones have an overall neutral charge? Which ones are hydrophilic?
Group 1: Hydrophobic amino acids
-nonpolar R groups, overall neutral charge at physiological pH
-the group with the most members
Group 2: Polar amino acids
-polar R groups, overall neutral charge
-some can be phosphorylated (serine/tyrosine)
-cysteines (SH) group can form covalent disulfide bonds
Group 3: Positively charged AA
-positive R groups at physiological pH, hydrophilic
-referred to as basic AA (side chains have nitrogen)
-involved in protein ion channels
Group 4: Negatively charged AA
-negative charged R groups, hyrophillic
-referred as acidic amino acids
-involved in ion channels
-has the least members (2/20)
P1:Be able to identify peptide bonds within a polypeptide chain.
(slide 19) connects two r groups/ in the middle of them
-often connecting a carbon or nitrogen
P1: How do fibrous proteins and globular proteins differ? How are they similar?
-proteins are grouped by shape
-fibrous (simple shape): structural roles (filaments or tubules)/ assist with spatial organization/ serve as anchoring junctions
-globular (complex shape): regulatory or chemical roles/ serve as enzymes or transporters/receptors
P1:How does the hydrophobic effect impact protein folding?
-hydrophilic AA: protein exterior
-hydrophobic AA: protein interior (move inwards to avoid water)
-stabilization relies on noncovalent interactions (hydrogen bonds, salt bridges, van der Waals)
-in a nonpolar environment, the opposite composition
-hydrophobic effect drives the folding
P1:Define “chiral”. Explain why isomer selection matters for pharmaceuticals.
Chiral: asymmetric in that structure and mirror image not superimposable
-the L isomer of AA is slightly more soluble and is easier to bind/transport
-isomer selection means maximizing drug efficacy
-L isomer active versus d isomer is not or harmful
-isomer selection means to minimize undesirable side effects
P1:Know which standard AA is achiral and why.
Glycine is the only AA achiral due to identical hydrogens as the side chains.
P1: Define “buffer”. Why are proteins often involved in buffer systems?
Buffer: a solution that resists changes in pH due to an acid-base conjugate pair
importance: small pH changes can have major metabolic implications, organisms tightly control their internal environments
ex. phosphate buffer system
-proteins are involved in buffer systems as can be H+ acceptors or donors, due to the presence of dipolar ions
P1:Do all of the standard proteinogenic AA have ionizable side chains? Are AAs with ionizable side chains found in all four groups?
-seven AA have readily ionizable side chains (aspartate, glutamate, histidine, cysteine, tyrosine, lysine, arginine)
-can form ionic bonds and participate in acid-base catalysis (group 2: polar, group 3: Positive, group 4: negative)
P1: If given a pH and pKa value, be able to determine a free AA’s ionization state and net charge.
- smaller pKa= stronger acid
-carboxyl group: pKa 2
-amine group: pKa 9
pH> pKa = deprotonated
pH< pKa = protonated
P1: Where does a protein’s net charge come from? Why does pH impact it?
-bc peptide bonds between the carboxyl group of one amino acid and the amine group of another, those groups don’t retain ionization states
-protein charge comes from ionizable side chains and terminal ends
-many biochemical reactions take place only within a narrow pH range
P2: Know the four levels of protein structure, and whether each relies mostly on covalent bonds or noncovalent interactions for stability.
- Primary Structure
-depends on covalent peptide bonds - Secondary structure (alpha helix and beta sheet)
-a repeating structure formed by rating two single covalent bonds on either side
-stabilized by hydrogen bonds between carboxyl and amine group - Tertiary structure
-stabilized primarily by noncovalent interactions (including hydrophobic interactions) - Quaternary structure
-stabilized by same chemical bonds as tert structure
-cross-linking between adjacent subunits may also occur via salt bridges or disulfide bonds
P2: Are most peptide bonds in the cis or trans configuration?
in the primary structure, peptide bonds, are usually in the trans configuration
-minimizes steric clashes between neighboring side chains
P2: Understand why peptide bonds do not rotate.
primary structure, amino acids are stabilized by uncharged peptide bonds= allowing for tight folding/ packing
-planar bonds with partial double-bond character, so rotation is prohibited (rigid and secure)
P2: Be able to identify which amino acid bonds rotate to form secondary structure.
-Carbon atoms in single bonds rotate freely.
-peptide bonds btw AA: DO NOT ROTATE
-covalent bonds within AA: DO ROTATE
Alpha helix: proline, glycine, aspartate and cysteine can be accommodated into a helix
-cause kinks due to size or irregular geometry
Beta sheet: all amino acids can be accommodated, distribution within the sheet will vary
P2: How do alpha helices and beta sheets differ? How are they similar?
Alpha helix: rod-like structure/ tightly coiled backbone
-Side chains extend outward in a helical way
- the majority have right-handed screws
Beta sheet: extended, zigzag structure
-side chains extend above or below in alternating pattern
-an anti-parallel arrangement in proteins most stable
-both are stabilized by hydrogen bonds
P2: Know which modifications (phosphorylation, glycosylation and fatty acylation) are done to an amino acid’s side chain versus to the polypeptide’s terminal end.
1 . Phosphorylating: the SIDE CHAIN of certain amino acids (alters protein function) - not alpha carbon
- Glycosylation: adding carbohydrate monomers to the exterior of monomer (glycoprotein)
- Fatty acylation: adding to the exterior of protein (proteolipids)
P2: What level of structure does a denatured protein retain?
retain primary structure: lose secondary, tertiary and quaternary
-enzyme activity reduced or lost as active site compromised
P2: Understand “sequence specifies conformation” and its exceptions.
- central principle: the order of AA in a polypeptide chain determines the protein’s 3D shape (the native state structure is most thermodynamically stable)
- for some proteins, the primary structure does not dictate the tertiary structure
-intrinsically unstructured proteins assume a structure based on interaction with other molecules (secondary structure)
-metamorphic proteins have two or more native states that are of equal energy, dual folding proteins (tert structure)
P2: Define “prion”. Do prions adhere to “sequence specifies conformation” or not? Why?
-misfolded pathogenic proteins/ infectious as able to transmit misfolding to other proteins of the same type
-highly resistant to proteases
-no, does not follow the central principle because it has very deadly effects. Does not adhere to the protein’s normal native state (the properly folded, assembled and biologically functional protein)
P3: Understand how the types of reversible and irreversible inhibitors differ.
Reversible inhibitors less specific; inactivate diverse protein types
Irreversible inhibitors more specific; inactivate specific protein types
P3: Be able to identify if end product feedback inhibition is used in regulation in a schematic.
End product interacts with e1 (allosteric) removed from active site. (negative feedback loop)
- Enzyme regulation may involve availability of cofactors and/or effectors
- Inhibited pathway using end product
And allosteric by feedback inhibition
P3: Be able to identify if a reaction is reversible or irreversible in a schematic.
Rapid dissociation of enzyme-inhibitor complex
enzyme-inhibitor complex stabilized by noncovalent interactions
3 common types of reversible inhibition - competitive, uncompetitive, noncompetitive
P3: Why are cofactors important?
small non-protein molecules essential for enzyme activity, may be metal ions or derived from vitamins. enzyme “helpers”, not permanently modified by enzyme - different enzymes performing similar chemical reactions can use the same cofactor
P3: How do coenzymes and minerals differ?
Metal ion cofactor= mineral
Vitamin dervided cofactor= coenzyme
————————————————————-
Cofactors that are metal ions - called minerals. May be grouped as major or trace. metal ions are cofactors for several critically important enzymes. - DNA polymerase, hexokinase and adenylate cyclase (all require Mg2+)
- complexes I to V of electron transport chain (require Fe-S clusters)
- stored mainly within liver and bones
P3: Be able to distinguish exergonic and endergonic reaction graphs
Positive ΔG°’: reaction endergonic, does not proceed spontaneously
Negative ΔG°’: reaction exergonic, does proceed spontaneously
P3: What are the four common catalytic strategies / mechanisms of enzymes?
- Covalent catalysis
- active site contains a nucleophile that is briefly covalently modified - general acid-base catalysis
- amino acids with ionizable side chains act as general acids or bases - Metal ion catalysis
- ions (like Fe2+, Cu2+, Zn2+, and Ni3+) serve as an electrophilic catalyst, generate a nucleophile, or bind to the substrate - Catalysis by approximation and orientation
- 2 substrates brought closely together to facilitate reaction
P3: Define “active site”. Know what features all active sites share.
Location on enzyme where substrate binds and where chemical reaction takes place.
- Are 3D crevices formed by multiple amino acid residues
- Constitute a small portion of the enzyme’s total volume
- Create unique microenvironments; water usually excluded
- Involve a large number of noncovalent interactions
P3: Explain why changing temperature, pH and salt concentration impact enzyme activity.
Temp - most enzyme-catalyzed reactions increase with increasing temperature - greater kinetic energy so enzyme/substrate interaction more likely
pH - most enzyme-catalyzed reactions occur within a narrow pH range. maintains ionization state for protein conformation and net charge. above or below optimal pH, enzyme activity reduced or lost
Salt concentration - cells generally isotonic (<0.9% salt), ions compete with amino acid residues to form noncovalent interactions, at certain concentration, protein denatures; enzyme activity lost
P3: Is ATP hydrolysis an exergonic or endergonic process?
Exergonic
P3: How does ATP’s phosphoryl-transfer potential compare to that of other biological important molecules?
- ATP phos. potential is in the middle. When compared to phospen. which ahs a better transfer potential due to a high negative delta G)
Tendency to transfer phosphate group to an acceptor molecule
due to structural differences between ATP and its hydrolysis products.
phosphoenolpyruvate hydrolysis ΔG°’ = -14.8 kcal mol-1
ATP hydrolysis ATP -> ADP + Pi ΔG°’ = -7.3 kcal mol-1
ATP -> AMP + PPi ΔG°’ = -10.9 kcal mol-1
Glucose 6-phosphate hydrolysis ΔG°’ = -3.3 kcal mol-1
P3: Do enzymes alter ΔG°’? What about Keq?
Enzymes do NOT affect ΔG, as free energy of product(s) not altered
Enzymes do NOT affect reaction equilibrium constant (Keq)
P3: Know how to determine an enzyme’s preferred substrate using KM values.
- KM is independent of [E]
- When [S] at KM, then enzyme at 1/2 Vmax
- Measure of enzyme substrate affinity with smaller KM - greater affinity
- Vmax and KM both influenced by environmental conditions
P3: Understand why increasing reactants, or removing products, can be used to ensure a readily reversible pathway goes in the “correct” direction.
Thermodynamics! reactions proceed towards equilibrium - pathway direction is from higher to lower energy. The number of products is greater than number of reactants. Equilibrium inpacted by increasing reactants, removing products, altering environmental conditions, etc.
P3: How do allosteric enzymes differ from Michaelis-Menten enzymes?
Michaelis-menten: have a single active site, generally catalyze 1 substrate reaction, governed by mass action, catalyze readily reversible reactions, not regulatory in nature
Allosteric: multiple active sites, catalyze multi-substrate reaction, governed by -environmental signals, more complex enzyme kinetics and quaternary structure. regulatory in nature and catalyze irreversible reactions like committed steps
(these 2 are almost flip flopped)
P3: T vs. R state
T (inactive) or R (active)
inactive - low substrate affinity
active - high substrate affinity
P3: Allosteric site
Have multiple active sites, so generally catalyze multi-substrate reactions
Activity governed by: (i) environmental signals, (ii) more complex enzyme kinetics, and (iii) a quaternary structure
Regulatory in nature, as catalyze irreversible reactions like the committed step in a pathway
P3: Negative vs. Positive effector
effectors are small molecules that bind and alter enzyme activity
positive effectors (i.e. activators)
negative effectors (i.e. inhibitors)
P3: Feedback inhibition
Reaction product (often final product) binds to allosteric enzyme, altering catalytic activity
P3: Vmax
maximal velocity
influenced by environmental conditions
Vmax is dependent on [E]
When enzyme at Vmax, then all available enzyme bound to substrate
P3: Transition state vs. Reaction intermediate
Enzymes lower a reaction’s activation energy (EA)* which facilitates the formation of the transition state
If more molecules reach transition state, then more product formed faster
Differs from intermediate as higher free energy (in energy saddle point)
P3: Activation energy (EA)
Initial energy input required for a chemical reaction to occur
P3: Gibb’s free energy (ΔG)
Whether or not the reaction occurs depends on Gibb’s free energy (ΔG)
ΔG = measure of useful energy that describes spontaneity of a reaction
Provides no information about reaction rate
Enzymes do not affect ΔG, as free energy of product(s) not altered
P3: Entropy
Entropy of universe always increases (2nd law) – cannot decrease
P3: Substrate
Type of ligand (i.e., molecule that binds to another [often larger] molecule for a biological purpose)
molecule chemically modified by enzyme during reaction
P3: Why aren’t Michaelis-Menten enzymes used to regulate a pathway?
These enzymes have a single active site, so generally catalyze 1-substrate reactions. Activity governed by mass action - catalyze readily reversible reactions thus enzymes conforming to Michaelis-menten kinetics are NOT regulatory in nature
P4: Understand how dietary proteins are digested. Do humans store AAs?
Must come from diet, cannot be synthesized by humans. Pepsin cleaves proteins into fragments (oligopeptides) responsible for 10-15% of dietary protein degradation. Digestion within stomach stimulates the gallbladder to release bile salts
AA are NOT stored for later use
P4: Define “oxygenase”. Why is this enzyme necessary for metabolizing phenylalanine, tyrosine and tryptophan?
enzyme that oxidizes a substrate by transferring oxygen to it
Phenylalanine is converted into tyrosine by a monooxygenase
tyrosine then metabolized to fumarate and acetoacetate
tryptophan converted into acetoacetate by a dioxygenase
P4: Does amino acid synthesis utilize the keto acids from glucogenic or ketogenic AAs?
Remaining amino acids considered both glycogenic and ketogenic
P4: How does a keto acid differ from an amino acid?
- Ketogenic amino acid - yield major metabolic intermediates for fatty acid synthesis or cellular respiration (generate ATP)
- Glucogenic amino acids- yield major metabolic intermediates for gluconeogenesis (generate glucose or cellular respiration (generate ATP)
P4: The urea cycle generates fumarate. What happens to this molecule?
fumarate is an intermediate of the citric acid cycle and can also be converted into oxaloacetate (via malate) in mitochondria
P4: Why is N-acetylglutamate (NAG) required for CPSI activity?
In mammals, CPSI requires cofactor N-acetylglutamate (NAG) functions as a positive effector; CPSI cannot convert ammonia otherwise, NAG synthesis is stimulated by the amino acid arginine
P4: What biomolecule monomer can be synthesized from aspartate, glycine and glutamine?
all 3 for de novo nucleotide synthesis
aspartate forms argininosuccinate but generates oxaloacetate
glycine generates pyruvate
glutamine generates alpha-ketoglutarate
P4: Do digestive enzymes cleave covalent bonds or noncovalent interactions?
Digestive enzymes break covalent bonds in protein-containing foods.
P4: Can humans metabolize essential AAs? What about nonessential?
Essential - must come from diet, cannot be synthesized by human enzymes.
Nonessential - Can synthesize from human enzymes; do not need to come from diet
P4: The urea cycle generates urea. What happens to this product?
Arginine hydrolyzed into urea and ornithine and polar urea is excreted from body in urine and nonproteinogenic ornithine transported back to mitochondria
P4: Where (organ(s) and organelle(s)) does the urea cycle occur in humans?
Begins in liver mitochondria then to cytoplasm then out by urine or back to mitochondria
P4: Can all 7 major metabolic intermediates be metabolized via cellular respiration?
Yes, but may not always metabolize that way.
Glucogenic amino acids yield major metabolic intermediates for gluconeogenesis (generate glucose or cellular respiration (generate ATP)
Ketogenic amino acids yield major metabolic intermediates for Fatty acid synthesis or cellular respiration (generate ATP)
P4: Know the 7 major metabolic intermediates, and which can be used to synthesize new fatty acids versus new monosaccharides
Pyruvate, α-ketoglutarate, fumarate, succinyl CoA, oxaloacetate, acetyl CoA and acetoacetyl CoA
Fatty acids can be synthesized by Acetyl CoA & acetoacetyl CoA
P4: Glucogenic vs. Ketogenic AA
Glucogenic amino acids yield major metabolic intermediates for gluconeogenesis (generate glucose or cellular respiration (generate ATP
Amongst proteinogenic amino acids, 13 considered glucogenic
Ketogenic amino acids yield major metabolic intermediates for Fatty acid synthesis or cellular respiration (generate ATP)
Amongst proteinogenic amino acids, only 2 considered ketogenic (i.e., leucine and lysine)
P4: CPSI
carbamoyl phosphate synthetase I
allosteric enzyme
In mammals, CPSI requires cofactor N-acetylglutamate (NAG)
Functions as a positive effector; CPSI cannot convert ammonia otherwise
P4: Transamination vs. Deamination
First step involves removing nitrogen via transamination
α-amine group transferred to α-ketoglutarate, forming glutamate
Glutamate then deaminated to regenerate α-ketoglutarate and yield NH4+
Ammonium ions (NH4+) enter urea cycle
Glycine, serine and threonine can be directly deaminated
P4: Albumin
a water soluble protein that transports amino acids by blood
Protein also transports fatty acids, bilirubin, calcium, etc.
P4: Bile salts
-Not enzymes but act as protein-destabilizing agents within small intestine
-Interfere with bacterial disulfide bonds or membrane stability
-Important against foodborne pathogens
-Also help with absorption of dietary lipids and Fat-soluble vitamins
-Digestion within stomach stimulates the gallbladder to release bile salts
P4: Specific vs. Nonspecific protease
specific protease as cleaves by large hydrophobic amino acid residues
nonspecific protease, preferential cleavage after phenylalanine and tryptophan
P4: Complete protein food
then contains all essential amino acids
- Cannot be synthesized by human enzymes; must come from diet
P5: Which AA donates its α-amine group to form most other AAs?
Glutamate donates it alpha amine group to form most amino acids via transamination
P5: Understand how nonessential amino acid synthesis is regulated. **check
-regulation: may involve cumulative feedback inhibition
(usually, pathways are regulated by feedback inhibition)
-needs at least two other amino acids to act as suppressors
P5: Understand how a protein is synthesized. What happens at each stage?
-Gene expression(DNA-RNA-Protein)
-synthesis occurs in Cytoplasm (prokaryotes); ER (eukaryotes)
- Begins at start codons
- involves ribosomes, mRNA, tRNA
- Initiation, Elongation and termination
P5: Are all genes in an organism expressed via translation at once?
Translation occurs on per gene/ small group of genes basis
P5: Understand how translation is regulated
via molecules involved in protein synthesis (translation)
-binding of poly(A) binding proteins on mRNA
-sequestering of mRNA in the cytoplasm or processing bodies
-methylation of rNA
-phosphorylation of protein initiation factors
-RNA interference (RNAi)
P5: Is the liver the only in the human body capable of synthesizing amino acids?
No!
-different nonessential amino acids are synthesized by different organs (synthesis=anabolism)
-liver: alanine, glutamine, arginine, tyrosine
-brain: glutamate, serine, proline
-kidneys: glycine, cysteine, asparagine, aspartate
P5: Where do humans obtain most of the nitrogen our bodies need for amino acid synthesis?
majority of nitrogen through diet
P5: How is nonessential amino acid synthesis are synthesized
Synthesis of the nonessential amino acids depends mainly on the formation of appropriate α-keto acids, which are the precursors of the respective amino acids. (cellular respiration is a main source of several keto acids)
-synthesized via transamination: glutamate donates the alpha amine group
-de novo AA synthesis: glutamate to glutamine
-cofactors are vital for synthesis
P5: Besides ribosomes, what other proteins are involved in translation/ what are their roles? **Check
Ribonucleoprotein: particles that consist of small/large subunits
mRNA:
tRNA:
P5: Where in a cell does translation occur in eukaryotes versus in prokaryotes
prokaryotes: cytoplasm
eukaryotes: ER
P5: How do silent mutations and missense mutations differ? How are they similar?
silent: same amino acid/ synonymous mutation (goes unnoticed)
Missense: different amino acid/ nonsynonymous (the new amino acid is coded for)
-both involve changes to an individual and specific codon/ can switch chemical groups
-alters the sequence of mRNA
P5: Do start codons calls for an amino acid? Which ones? What about stop codons?
-methionine/ AUG: start codon initiating translation
-UAA, UAG, UGA: stop codons/ DO NOT code for an amino acid
P5: Can a person’s body synthesize a protein that contains essential amino acids
Humans can only synthesize nonessential amino acids, essential amino acids acquired from diet
P5: Ester linkages are relevant to EF-Tu and RF1. What is the connection for both?
*need notes
What is the meaning of a complete protein food
we must get the other nine amino acids (called “essential amino acids”) from the foods we eat. When a food contains all nine of these amino acids, it is called a “complete protein.”
what does albumin mean
Albumin is the most common protein found in blood plasma. It helps to ensure blood stays in arteries and veins, and helps carry hormones, vitamins, and enzymes throughout the body
Albumin is made in the liver and quickly carried to the bloodstream.
what is the difference between glucogenic vs. ketogenic AA
glucogenic amino acids produce pyruvate or any other glucose precursors during their catabolism
ketogenic amino acids produce acetyl CoA and acetoacetyl CoA during their catabolism.
what is the nitrogenase enzyme complex
Nitrogenase is a complex, bacterial enzyme that catalyzes the ATP-dependent reduction of dinitrogen (N2) to ammonia (NH3).
what is the peptidyl transferase center
resides in the large ribosomal subunit and catalyzes the two principal chemical reactions of protein synthesis: peptide bond formation and peptide release.
