Cell Biology Chapter 4A

how many amino acids are there

20

t/f structure determines protein function

true

what is the configuration of the side chains in a protein

trans

what is the directionality of peptide chains

n(amino) terminus to c(carboxyl) terminus

backbone model

core bonds

ribbon model

coils and sheets for alpha helix and beta sheets

wire model

positions of the side chains

space filling model

accurate surface and shape

how do alpha helixes and beta sheets form

hydrogen bonding between amine and carbonyl groups

what is a coiled coil

when two or three alpha helices wrap around eachother

examples of coiled coils

keratin and collagen

chaperone protein

guide the folding of newly synthesized polypeptide chains

denaturation

disrupting the confirmation of a protein. can be chemicals, heat, ph

can denaturation be reversed

yes, only if chaperon protein is not denatured

what is a domain

portion of a protein that can fold up to a tertiary state independently

what do domains do

hydrolyze ATP and bind to DNA

what is a subunit

when two or more polypeptides interact to reach a quaternary structure

how do hydrophobic interactions influence protein shape?

nonpolar r groups cluster into center and away from water

how do hydrogen bonds influence protein shape?

polar r groups link with water or other polar side chains

how do ionic bonds influence protein shape?

oppositely charged r groups (+ and -) attract one another and form salt bridges

disulfide bonds

covalent links between cysteine sulfur atoms

what is the native conformation of a protein

most energetically favorable and releases the most free energy and forms the most noncovalent bonds

where are disulfide bonds catalyzed?

rough ER

which proteins are exposed to harsher env

extracellular

what holds extracellular proteins together?

disulfide bridges

what are serine proteases

family of proteolytic (protein cleaving) enzymes and blood clotting. subtle differences in shape and sequence help optimize various jobs

dimer

two polypeptides interact

homodimer

two identical subunits interact

heterodimer

two different subunits interact

possible shapes that a protein subunit can make

filament. spherical shell, and hollow tube

where are viruses housed

protein cages

role of collagen and where it is found

provides structural stability in extracellular matrix

what happens when protein misfolding occurs in prion diseases

amyloid plaques form and stack by triggering neighboring cells and spreading the propagation

what forms in alzheimers

tangled filamentous plaques

what happens in alzheimers disease with proteins

amyloid precursor protein is cleaved into short fragmented beta amyloid proteins that changes confirmation into alpha helix. these are highly stable and aggregate, forming plaques

__ are the most structurally complex and functionally diverse macromolecules in cells

proteins

protein folding is driven by ___ and favors the conformations stabilized by ___

thermodynamics, noncovalent interactions

job of fibrous proteins

structural support

job of globular proteins

dynamic functions such as catalysis, regulation, transport, and signaling

what is the disease modifying monoclonal antibody used to treat early stages of alzheimers

lecanemab

how does lecanemab work

binds to and helps immune system clear beta amyloid protein clusters that build up int he brain

effect of lecanemab

18 months decline

how is lecanemab given

intravenous infusion every two weeks

what is the humanized IgG1 monoclonal antibody that binds to insoluble n-trucated pyroglutamate amyloid betaa

kisunla

mechanisms for kisunla

1. targets specific amyloid cells

2. recruits immune cells

3. removes plaque

4. stops treatment