Proteins & pH Flashcards
What is the isoelectric point (pI) of a molecule ?
The pH at which a molecule has no net charge.
What is the Henderson-Hasselbalch equation?
The Henderson-Hasselbalch equation is: pH = pKa + log([conjugate base]/[conjugate acid])
What is retrotranslocation?
Retrotranslocation is the transport of a misfolded protein from the endoplasmic reticulum (ER) to the cytoplasm.
What is ubiquination?
Ubiquination is a form of a post-translational modification in which the ubiquitin protein is attached to a substrate protein on a lysine residue. It is a three-step process involving three enzymes: ubiquitin-activating enzyme (E1), ubiquitin-conjugating enzyme (E2), and ubiquitin-protein ligase (E3). Polyubiquination leads to the initiation of proteolysis of the substrate by serving as the recognition signal for a proteosome.
What is the clinical significance of the ubiquitin-proteasome pathway?
The ubiquitin-proteosome pathway plays an important role in maintaining cell homeostasis. Changes in this process can lead to the formation of tumors (e.g., hemangioblastoma, renal cell carcinoma, colorectal cancer) and neurodegenerative diseases (e.g., Alzheimer disease, amyotrophic lateral sclerosis, Parkinson’s disease).
What is the molecular mechanism underlying prion diseases?
Prion diseases result from the conversion of a normal, cell-surface glycoprotein (PrPc) into a conformationally altered isoform (PrPSc) that is infectious in the absence of nucleic acids. PrPSc is protease-resistant and infectious while PrPc (normal form) is not. PrPSc also has more beta-pleated sheets in it’s structure (40% compared to 3% in PrPc).
