8/9/17 and some 10 Flashcards
Heme favor O2 relative to CO
Ligand constrained to bind in bent fashion, normal for O2 but not CO
CO only binds slightly better
Mb vs Hb
Mb a monomer, Hb a tetramer
Mb stores 02 while Hb transports it
O2 dissociation curves
Mb has higher oxygen affinity, reservoir for oxygen in skeletal muscles
Hb has sigmoidal curve that demonstrates cooperativity
T and R state
T is low oxygen
R is high oxygen
Proximal His
F8 from N terminus
His 87 each alpha helix
Oxygen binding
Fe2+ binds to proximal His and is above the plane of the ring
Oxygen pulls Fe2+ back into ring plane and moves the helix with the proximal His
Subunit interface interactions
Tetramer functions more so like a dimer of dimers
A1B1 = A2B2
A1A2
A1B2 = A2B1
B1B2
T state stabilization
A1B2 interface:
His B146 with Lys A40
A1A2:
His A122 with Asp A126
Allosteric Inhibitors of Hb
Shift dissoc curve right, more oxygen unloading in tissues
pH
Intracellular cons of 2,3-bisphosphoglycerate (BPG), binds to Beta subunits
CO2 binding to Hb
Bohr Effect
Effect of pH on Hb oxygen affinity
Only acid Bohr effect works
More acid means less oxygen bound
T state has greater affinity for protons than R state from His residues
Short term adjustment to high altitude
Up intra-erythrocytes conc. Of BPG
BPG comes from increased glycolytic activity
Role of inspire
Uncharged so pass into RBCs and converted to BPG to help increase the depleted levels
CO2 transport
Carbamoylation of the N terminal
Stabilizes T state over R
NOT by binding to heme
Carries CO2 from tissues to lungs, also does H+
Screening
Presumptive identification of unrecognized disease or condition by tests or other procedures
Perform on healthy people, not used for diagnostic
Types of disease prevention
Primary: prevent disease before it starts, before disease onset
Secondary: delay symptoms, onset to symptom appearance
Tertiary: slow disease progression, symptoms to death
Validity types
Internal: measure what supposed to
External: how well result generalize to rest of the population
Test sensitivity
Number of people who screen positive divided by the number of people actually with the disease
Optimize to prevent disease transmission
Test specificity
Number of peps who screen negative among those who actually don’t have the disease
Optimize for fatal disease with no treatment
Predictive values
Positive: peps with disease that tested positive divided by all positive tests
Negative: peps with disease that tested negative divided by all negative tests
miRNA
Regulate mRNA by degrade or inhibit translation if same or complementary to miRNA sequence
7SL RNA
Protein targeting
Forms ribonucleoprotein complex with 6 proteins to make signal recognition particle to move new protein to ER
TATA box
TATA Binding Protein is part of TFIID
Cis-acting element that serves as a spot for a promoter to bind for increased transcription
TBP is saddle shape that bends DNA sharply
Enhancer
Independent of distance of transcriptional start, IND of location, and IND of orientation
Segment of DNA that increases transcription
Promoter
DNA that binds to RNA polymerase and controls transcription
Switch for on or off that can be positively or negatively regulated
Trans-acting factor
Protein factor that binds to cigs-acting elements
RNA polymerase for mRNA
Pol II, prokaryotes only have one pol for all RNA types
Features of transcription
No primer is required, unlike DNA replication
Synthesized 5’ to 3’ and only use one strand of DNA for template
Template strand is the DNA strand that runs from 3’ to 5’
Transcriptional start site
First nucleotide of Exon 1, upstream DNA would be the promoter
Does RNA polymerase unwind DNA?
Yes, and then rewinds when move past
PolyA addition
Endonuclease recognizes AAUAAA and cleaves RNA downstream
Polyadenylate polymerase then adenylates the residue
Genomic imprinting
Methylated CpG of one parental allele
Cytosine is methylated in CpG
Look at last slide of 2nd articulate on Thursday 8/10
mRNA stability for post-transcriptional regulation
RBC
When cellular iron conc. Is low, protein binds to 3’ end of transferrin receptor mRNA and prevents it from being degraded, results in increased iron conc.
Translational regulation of RBCs
Globin protein synthesis is regulated by the heme conc.
Regulated at initiation of translation
Little heme means little globin synthesis
What explains X inactivation?
DNA methylation
Actinomycetes D
Intercalated in DNA so bad template for RNA synthesis, transcription inhibitor
Works in both prokaryotes and eukaryotes
Rifamyacin or rifampicin
Interferes with formation of first phosphodiester bond , inhibit initiation of RNA synthesis
Only affects prokaryotes
Alpha-amanitin
Binds to RNA Pol II so blocks eukaryotic transcription
Mushroom
Prokaryotic protein synthesis inhibitors
Inhibit translation
Tetracycline: block A site and inhibits binding of charged tRNA
Chloramphenicol: inhibits peptidyl transferase activity
Erythromycin: binds to 50S subunit and inhibits translocation
Streptomycin: causes misreading and inhibits translation
Neomycin, kanamycin, gentamycin: interferes with 16S rRNA
Both Prokaryotic and Eukaryotic protein synthesis inhibitors
Inhibit translation
Structure similar to the 3’ end of an amino-acyl tRNA, binds to empty A site, peptide with puromycin at C terminus
Eukaryotic protein inhibitors
Inhibit translation
Cycloheximide: blocks peptidyl transferase activity
Diphtheria toxin: 2 polypeptides covalently modify translocase to inactivate translocation, immunization against this bacterial toxin is universal in US
Ricin: inactivated the 60S subunit of the eukaryotic ribosome
Systemic lupus erythematosus
SLE
Auto-immune disease that causes chronic inflammation, snRNPs are targets of the antibodies
Joint pain and swelling, butterfly rash on cheeks
Testicular feminization
XY with androgens
Lack androgen receptor
Man boobs
Chronic myeloid nous leukemia
Translocation between chromosomes 9 and 22, Philly Chromosome
Cancer of white blood cells
Methotrexate
Treats cancer by inhibiting dihydrofulate reductase to produce inadequate amount of thymine and stop cell proliferation
Resistance by gene amplification of DHFR gene to dampen the effects of competitive inhibition
Vitamin deficiency anemia
Vitamin B12 for Hemoglobin production is needed
Hemolytic anemia
Destruction of RBCs for various reasons
Aplastic anemia
Rare, bone marrow fails to produce all types of blood cells
HbS Polymerization factors
Intracellular Hb composition, higher % of HbS has higher polymerization
Intracellular Hb conc., higher HbS conc. Has greater polymerization, dehydration makes worse
Oxygenation, polymerization favored at low oxygen saturation, acidosis promotes polymerization cuz makes HbS deoxygenation
Clinical manifestations of sickle cell
Anemia, frequent infections, joint pain, dyspnea, leg lesions heal poorly, vaso-occlusive crises, severe pain
Short term sickle cell treatments
Hydration, oxygenation, narcotic analgesics, exchange transfusions, antibiotics
Long term sickle cell treatments
Iron chelators, hydroxyurea, bone marrow transplantation, antioxidants, gene therapy
Inosine
Converted to BPG in cell
Used for stored blood
