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MCB2 Block 2
N/A
95
Biochemistry
Professional
06/15/2012

Additional Biochemistry Flashcards

 


 

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Term
Proximal histadine
Definition
Forms bonds with Fe2+ on alpha helix
Term
Distal histadine
Definition
Forms weak bone with O2
Term
HbA
Definition
Major adult Hb (glu on B chain)
Term
HbS
Definition
Glu --> val on B chain
Term
HbC
Definition
Glu --> lys on B chian
Term
HbA1c
Definition
Nonenzymatically glycosylated alpha and beta chains at N'; marker of diabetes mellitus, hyperglycemia
Term
Fe3+
Definition
Reduces O2 affinity therefore is useless as an O2 transporter; excessive methemaglobin formation
Term
RBCs defend against oxidation of heme Fe2+ via:
Definition
Ascorbate (Vitamin C), glutathione; proper binding of heme creating protective environment; methemoglobin reductase
Term
Ascorbate (vit. C), glutathione
Definition
React with oxidative agents before they can react with and care damage to Hb Fe2+
Term
Methemoglobin reductase
Definition
Reduces methemaglobin to normal hemoglobin; requires NADH coenzyme (Fe3+ + NADH, H --> Fe2+ + NAD+)
Term
Congenital methemoglobinemia (HbM)
Definition
Abnormality in heme binding pocket of alpha or beta chain due to substitution of proximal histadine by tyrosine
Term
Hb "R" conformation
Definition
Binds O2 150-300x more tightly than does T conformation; O2 binding pulls proximal histadine causes T-->R conformation change
Term
Hb cooperativity and sigmoidal kinetics
Definition
As pO2 rises, heme #1 is oxygenated --> Hb shifts to R state with higher O2 affinity which allows binding of heme #2-4
Term
2,3-BPG
Definition
Negative effector of O2 binding to Hb; promotes unloading of O2 to tissues; rapidly rises in hypoxia; allows O2 unloading from HbA to HbF
Term
Binding of BPG to deoxyhemoglobin ("T")
Definition
Occurs via 8x histadyl groups ONLY on the beta chains
Term
CO2 binding
Definition
CO2 covalently binds terminal -NH2 of both alpha and beta chains
Term
Bohr effect
Definition
Major facilitator of O2 unloading in tissues
Term
Carbonic anhydrase
Definition
CO2 + H2O --> H2CO3
Term
Dissociation constant
Definition
Ka = [H+][A-]/[HA]
Term
Henderson-Hasselbalch equation
Definition
pH = pKa+log10 [A-]/[HA]
Term
When charge = 0
Definition
pH = pI
Term
Histadine (Imidazole)
Definition
Buffer parallels H2O's temperature dependent behavior
Term
Chloride-bicarbonate exchanger (anion exchange protein)
Definition
Increases membrane permeability >10^6; secondary active transport
Term
Transmembrane transporters ("cassettes")
Definition
Na/K ATPase, Ca2+ transporter, CFTCR (cyctic fibrosis transmembrane conductance regulator = Cl- transporter)
Term
Oxidoreductase
Definition
e- transfer via oxidation-reduction reaction
Term
Transferase
Definition
Transfer of functional groups to a substrate
Term
Hydrolase
Definition
Donor group transferred to water; catalyzes cleavage of bonds by addition of water
Term
Lyase
Definition
Addition of groups to double bonds/formation of double bonds by group removal; adds/removes water, ammonia, CO2
Term
Isomerase
Definition
Transfers group within a molecule; catalyzes racemization of geometric/optical isomers; chemical formula remains the same, freely reversable
Term
Ligase
Definition
Formation of bonds between -C,O,N,S via condensation reactions coupled to ATP
Term
Turnover number (Kcat)
Definition
Number of substrate molecules --> products/sec
Term
Transition metal cofactors
Definition
Zn2+, Fe2/3+, Mn2+, Cu2+/++; promote catalysis by binding substrate and promoting electophilic catlaysis at bond cleavage site or stabilizing intermediates in reaction sequence
Term
Q10
Definition
Vt+10/Vt1
Term
Michaelis-Menten equation
Definition
V = (Vmax * [S])/(Km + [S])
Term
Competitive inhibition
Definition
Increase in Km, no change in Vmax; statin, allopurinol
Term
Non-competitive inhibition
Definition
Decrease in Vmax, no change in Km
Term
Uncompetitive inhibition
Definition
Decrease in Km and Vmax; formation of permanent adduct (binds ES complex, not substrate binding site); organophosphates, aspirin, cholera toxin
Term
Organophosphates
Definition
Permanently binds to ACh-ase
Term
Aspirin
Definition
Inhibits COX1, 2 via permanent binding to a serine residue at active site
Term
Vtype enzymes
Definition
Change Vmax
Term
Ktype enzymes
Definition
Change Km
Term
Covalent protein modification
Definition
Cholera, Diptheria, Pertussis toxins
Term
Cholera toxin
Definition
Keeps adenylate cyclase 'on' via adenyl-ribosylation of key enzymes
Term
Diptheria toxin
Definition
Enzyme inhibits protein synthesis by modification of a crutial histadine residue of eEf2; most resurgent disease
Term
Pertussis toxin
Definition
ADP ribosylation of alpha subunit of G protein
Term
Phosphorylation/dephosphorylation sites
Definition
At reactive -OH groups on serine, threonine, tyrosine residues
Term
Creatine kinase
Definition
Specific for cardiac infarct
Term
Troponins
Definition
More accurate and reliable than creatine kinase; peaks at 8-28 hours
Term
Lactate dehydrogenase, glutamate-oxaloacetate transaminase
Definition
Appear long after tissue damate (not as useful as infarct-specific indicators)
Term
SGLT
Definition
Glucose cotransport driven by Na+ in intestinal epithelium, renal tubule
Term
GLUT-1
Definition
Heart, brain, placenta, RBC; hypoxia in muscle = increased activity; also transports vitamin C
Term
GLUT-2
Definition
Liver, kidney, pancreatic B cells, intestine; insulin independent
Term
GLUT-3
Definition
Neurons, kidney, placenta; also transports vitamin C
Term
GLUT-4
Definition
Muscle, apidocyte, heart; insulin dependent
Term
GLUT-5
Definition
Transports fructose; located in sarcolemma (muscle) or vesicles (spermatozoon)
Term
Glucokinase
Definition
Used at increased [glucose] due to increased Km
Term
Hexokinase
Definition
Used at decreased [glucose] due to decreased Km
Term
Phosphoglycerase kinase deficiency inheritance
Definition
X-linked
Term
PFK-1
Definition
Main regulatory enzymes of glycolysis
Term
Pyruvate kinase deficiency
Definition
Most common genetic defect causing hemolysis
Term
Glycogenesis Type VII (Tarui's disease)
Definition
PFK1 deficiency in skeletal muscle; inability to produce large amounts of lactose
Term
Major precursors of glyconeogenesis
Definition
Lactate, ketoacids (puruvate, OAA, alpha-KG derived from alanine, aspartate, glutamate), glycerol (from TAG), propionyl-CoA (from odd chain fatty acids)
Term
von Gierke's disease (glycogenosis I)
Definition
Deficiency in hepatic G6Pase leading to deep hypoglycemia and severe lactic acidosis ; uricemia leading to breakdown of puring nucleotides; xanthomata = increased serum lipids
Term
Muscle glycogen
Definition
No direct role in buffering plasma glucose; muscle lacks G6Pase
Term
Glycogen synthase
Definition
Only creates alpha-1,4 linkages always at the non-reducing end of a pre-existing chain
Term
Glycogenin
Definition
Attaches initial glucose from UDP-glucose at the OH group of a specific tyrosine; autocatalytic; occurs 8x, then glycogen synthase takes over
Term
Nucleoside diphosphate kinase
Definition
In mitochondrial intermembrane space: UDP + ATP --> UTP + ADP
Term
Glycogen phosphorylase
Definition
Use of Pi to create G1P from G6P; covalently bound pyridoxal phosphate in Schiff base (connection between lysine and coenzyme also seen in biotin)
Term
Schiff base
Definition
C=N bound to lysyl residye
Term
Debranching enzyme transferase activity
Definition
Transfers alpha 1,4 attached glucose to a pre-existing chain
Term
Debranching enzyme alpha-1,6 glucosidase activity
Definition
Hydrolizes branchpoint glucose as free glucose
Term
Acidic alpha-glucosidase
Definition
Lysosomal degradation of glycogen granules to free glucose; cleaves both alpha1,4 and alpha1,6 linkages
Term
Phosphoprotein phosphatases
Definition
Recognize all seryl-phosphate groups
Term
Type 0 glycogenoses
Definition
Glycogen synthase deficiency; hepatic disorder; fasting hypoglycemia, ketosis, unresponsive to glucagon
Term
Type IV glycogenoses (Anderson's disease)
Definition
Branching enzyme deficiency; progressive hepato-splenomegaly (muscle also affected); long needle-like straight chains of alpha1-4 linkages
Term
Type VI glycogenoses
Definition
Liver glycogen phosphorylase deficiency; X-linked; hepatomegaly
Term
Type VIII glycogenoses
Definition
Phosphorylase B kinase deficiency; involves muscle, liver
Term
Type V glycogenoses (McArdle's syndrome)
Definition
Muscle phosphorylase deficiency; effects skeletal muscle only; myoglobinuria, loss of creatine kinase --> renal failure
Term
Type III glycogenoses (Cori disease)
Definition
Debrancher deficiency; affects liver, muscle (hepatomegaly)
Term
Type I glycogenoses (von Gierke's disease)
Definition
G6Pase deficiency = insufficient free glucose; severe lactic acidosis; hepatomegaly; uricemia from excess purine breakdown (no conversion of lactate to glucose)
Term
Type II glycogenoses (Pompe's disease)
Definition
Acid alpha-glucosidase/acid maltase deficiency; lysosomal defect; muscle hypertrophy, CNS, liver affected; cardiomegaly, respiratory distress; floppy infant syndrome; no abnormalities in glycogen and energy metabolism
Term
Type VII (Tarui's disease)
Definition
PFK deficiency; elevated muscle glycogen; RBC hemolysis and hyperbilirubinemia
Term
PDH defect inheritance
Definition
X linked
Term
Pyruvate dehydrogenase complex
Definition
Inactivated with integral serine specific protein kinase (phosphorylated state); activated with integral phosphatase (dephosphorylated state); requires TPP
Term
Required coenzymes
Definition
TPP, FAD, NAD, CoASH, Lipoic acid (susceptable to arsenic poisoning)
Term
-SH groups
Definition
underog reversable oxidation/reduction
Term
Beriberi
Definition
lack of thiamin (B1)
Term
Citrate synthase
Definition
Driven by exogonic rupture of thioester bond
Term
Aconitase
Definition
Inhibited by Zn2+, fluroracetate (uncompetitive)
Term
Isocitrate dehydrogenase
Definition
Major regulator; irreversible; phosphorylation at critical serine prevents binding of isocitrate
Term
alpha-KG
Definition
Requires CoASH; arsenite binds reactive -SH group
Term
Succinate thiokinase
Definition
Substrate level phosphorylation
Term
Succinate dehydrogenase
Definition
Membrane bound; powerfully inhibited by aresenite binding exposed -SH group of cysteinyl residues
Term
Fumarase
Definition
Freely reversable
Term
Citrate
Definition
In liver, released from mitochondria to inhibit PFK1; in heart, 100% is used for ATP production
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