Block 1 enzyme + pathways Flashcards
Limited proteolysis
Peptide hormones (insulin)
Clotting factors
Digestive enzymes (pepsinogen etc)
Ubiquitination
tags for proteasomal degredation
Acetylations/deacetylation
done to histones to regulate transcription
Phosphorylation vs. dephosphorylation
kinases & phosphatases
Glycosylation
Process to make glycoproteins and proteoglycans (i.e folding N-glycans in the ER’s lumen)
Hydroxylation
Process to make collagen and elastin
ADP-ribosylation (bacterial toxins)
Bacteria that cause overactive signaling pathways for themselves to use:
cholera (Gs) + pertussis (Gi)
Bacteria that inhibit signaling pathways:
Diptheria (Gs)
O-glycosylation (post-translational)
Glycosyltransferase glycosylated the OH-groups of proteins in the Golgi forming:
Protein-OH +UDP—> Protein-O-Sugar—> Mature-O-glycans—-> Targeting action sites for protein
Cytosolic Protein pathway (post-translational)
Proteins are made from Free Ribosomes —-> completed synthesis —-> gains signal sequence and is translocated to its site of action
Secretory Protein pathway
Free ribosomes make protein —> growing protein gains ER signal sequence —> Signal recognition particles see SSand stop synthesis —> protein is translocated into the ER —> transcolon opens and inserts the growing peptide into the ER’s lumen —> protein synthesis re-starts —-> protein is modified in the ER then packaged into vesicles
if the vessicle is coated in:
COP I it goes Golgi—-> ER (re-do)
COP II it goes ER—->Lumen
Clarthrin it goes trans golgi —> Lysosome (destroyed)
A protein’s activity is altered when a particular serine side chain is phosphorylated. Which of the following amino acid substitutions at this position could lead to a permanent alteration in normal enzyme activity?
Ser —-> Glu
A 39-year-old male truck driver presents with an overdose of methamphetamine (pKa = 10.0) consumed in an attempt to be alert at night for long drive. Which of the following statements regarding the treatment of methamphetamine overdose is most appropriate?
.
Ammonium chloride acidifies the urine, converting a larger fraction of methamphetamine to the unprotonated, uncharged form, which is poorly reabsorbed and thus more rapidly eliminated.
A patient with influenza has a fever of 101.8°F orally. The excess heat is dissipated throughout the body via a substance that can be best described by which one of the following?
dipolar molecule
Proteins, which are composed of amino acids, help transport lipids in the bloodstream. These proteins need to be able to cluster with other non-polar molecules and exclude water. Which of the following would best describe the side chains of these amino acids in the lipid transport proteins?
positive hydropathic index
Aspirin (pKa = 3.5) is largely protonated and uncharged in the stomach (pH 1.5). What percentage of the aspirin will be in this form at pH 1.5?
99%
Which peptide is less soluble in an aqueous environment, Ala-Gly-Asn-Ser-Tyr or Gly-Met-Phe-Leu-Ala?
Gly-Met-Phe-Leu-Ala
What will happen to the charge on His residues in a protein that moves from the cytoplasm to lysosome?
pronated
Is Val ionized when incorporated into a protein?
it’s not ionized
What effect will raising pH from an acidic value to the physiologic value of 7.4 have on neutral amino acid?
Deprotonation of the alpha-carboxyl group
A patient attempted suicide by ingesting 50 aspirin tablets. This led to a fairly severe metabolic acidosis. A decrease of blood pH from 7.5 to 6.5 would be accompanied by which one of the following changes in ion concentration?
A 10-fold increase in hydrogen ion concentration
The results from the blood amino acid screen show two elevated amino acids. A titration curve performed on one of the elevated species shows two ionizable groups with approximate pKs of 2.0 and 9.5. The most likely pair of elevated amino acids consists of
Leucine and isoleucine
Collagen synthesis pathway
Intracellular: RER makes 3 prepocollagen an they’re translated —-> It’s ER signal sequence is cleaved via protease into procollagen —-> In the ER’s lumen the procollagen is hydroxylated by vitamin “C” and then “O-glycosylation to form a triple helix + disulphide bonds —-> Procollagen leaves the cell and extended ends are cleaved into tropocollagen which is assembled into fibrils —> fibrils are cross-linked via lysyl oxidase and mature to collagen
Collagen 1,2,3,4
1= tough bone,
2= cartilage
3= skin (elhers danlos type 2)
4= basement membrane (elhers danlos type 1)
Protein kinases phosphorylate proteins only at certain hydroxyl groups on amino acid side chains. Which of the following amino acids contain side chain hydroxyl groups?
serine, threonine, and tyrosine
