Rafferty 1 Flashcards
define and give the equation for pI (where there are 2pK values)
pI is the zwitterionic form of an amino acid. (pK1+pK2)/2=pKI
give the henderson-hasselbalch equation
pH=pKa+log([A-]/[HA])
enzymes enhance the rate to go to the e_______ point
equivalence
do enzymes increase or decrease the energy barrier for the forward and backward reactions?
decrease
what is an apoenzyme and a holoenzyme? what is the equation that relate these two forms of enzyme?
apoenzyme = enzyme without cofactor
holoenzyme = enzyme with cofactor that is catalytically active
apoenzyme+cofactor=holoenzyme
give the 2 types of cofactor
metals and coenzymes
define a coenzyme
subdivision of a cofactor - small organic molecule
give the 2 types of coenzyme and define them
cosubstrate - loosely bound coenzyme (binds and is released from enzyme like substrate/product)
prosthetic group - tightly bound coenzyme
define a cofactor
additional molecule that increases the number of available functional groups to aid catalysis
name and describe the 6 types of enzyme
- oxidoreductases: redox reactions eg by nad+
- transferases: functional group transfer (1 e-philic group from 1 nucleophile to another)
- hydrolases: specific transfer reaction via H2O addition
- lyases: addition/removal of groups to make double bonds
- isomerases: conversion between isomeric forms
- ligases: joining two molecules, requires chem energy source
what type of bond stabilizes IgG?
disulphide bridge
name the 6 domains in IgG
VL/VH/CL1/CH1/CH2/CH3
where to ab’s bind on IgG?
hypervariable beta-sheet loops on the N-terminal variable region
name and quantify the number of regions in IgG, how can these regions be separated?
2xFab 1xFc, split by papain
what are the 3 main functions of a membrane?
- separate cells from env
- internal membranes for boundaries of organelles
- env for critical biological processes
name the types of molecule that are membrane (im)permeable
permeable: gases/small uncharged polar (can be semi-permeable)
impermeable: large uncharged polar molecules/ions/polar molecules
name 3 main types of lipid
phospholipids, isoprenoids and glycolipids
which molecule can form a micelle?
fatty acids
what does increasing the alcohol content of a phospholipid membrane do?
increases its curvature
what is the effect of increasing double bond content in a fatty acid?
increases membrane fluidity
what is the effect of asymmetric lipid distribution in a membrane?
changes in membrane curvature
what is the effect of cholesterol in a membrane?
decreases fluidity - cholesterol has planar steroid ring which gives it mechanical stability
increased order - this is due to its planar, inflexible tail, which makes the phospholipids elongate - therefore increased membrane thickness
what is the effect of increasing order in a phospholipid membrane?
membrane increases in thickness - this is because the f/a chains straighten
what is the effect of increasing temperature in membrane containing cholesterol?
gel consistency becomes more fluid which decreases phospholipid order and therefore decreases in thickness
what is FRAP?
fluorescence recovery after photobleaching - experiment to quantify lateral protein and lipid movement within a plasma membrane
name and describe the 3 main membrane proteins
- integral: all/partly embedded in membrane, h.phobic exterior, need v specific detergent to remove from membrane (called solubilization)
- peripheral: at membrane boundary, interact with both other membrane proteins
- lipid anchored: f/a anchored in membrane via ester/amide link to protein OR isoprenoid group in membrane attached by cys residue to protein OR GPI linked to protein via c-terminus
why are alpha helices used in transmembrane proteins?
contain h.phobic residues
what is a hydropathy plot and why is it used?
the calculation of a/a seq of a protein to determine h.philic/phobic nature
name and describe the 3 transport proteins
- channels and pores- molecules diffuse through, channel mediated (which is unlike simple diffusion)
- passive transporters - with conc grad, carrier mediated
- active transporters - against conc grad uses chem energy
describe the linkages in the three lipid anchored proteins
lipid anchored:
- f/a anchored in membrane via ester/amide link to protein
- isoprenoid group in membrane attached by cys residue to protein
- GPI linked to protein via c-terminus
