proteins Flashcards
(29 cards)
what hormone is responsible for cells signalling?
insulin
what are the two enzymes involved in digestion and what are their functions?
trypsin-breaks down proteins
amalyse- breaks down starch into sugars
what are the two proteins involved in metabolism called and what are their functions?
alcohol dehydrogenase- metabolises ethanol
ICZA hexokinase- adds a phopsphate to glucose after glucose is taken up by the cell.
what is the oxygen transport protein called?
hemoglobin- binds to oxygen in the lungs and carries it in the blood to tissues for use in metabolism
what makes up an amino acid
an amino group, a carboxyl group and an R group side change which differs between different amino acids.
what does the PKA value indicate
the PKA is the ph at which ionisable group on an amino acid or protein is 50% ionised
what does the PI value indicate
isoelectric point is the PH where the net charge on an amino acid is zero
what is phosphorlylation doing
adding a phosphate group which controls enzyme activity, chemical on/off switch.
what is hydroxylation doing
needed to prevent connective tissue diseases and scurvy, often proline and lysine
what is carboxylation needed for
needed for blood clotting, glutamate often involved
what are the three peptide bond properties
planar, trans and dipole
what is the process of adding glucose to amino acids called?
glycosylation
what type of bond is a N-Ca and what are its features
a phi bond. free rotation, angle can be anywhere between 0 and 180.
can lead to O-O collisions
what type of bond is a C-Ca bond and what are its features?
a psi bond, free rotation.
can lead to NH-NH collisions
what is a omega bond and what is its properties?
C-N bond. Very limited rotation. closer to either 0 or 180.
a partial double bond
features of an Alpha helix
main chain spirals around central axis, right handed spiral
hydrogen bonds form between n+4 eg 3-7
how much is hydrogen bond energy and what is its purpose?
12-28kjmol and they help to stabilise a helix structure
features of a beta structure
each section of a B structure= a b strand
hydrogen bonding occurs between adjacent strands
2-10 strands per sheet
antiparallel= linear hydrogen bonds
parallel= non linear hydrogen bonds
what is a supersecondary structure and what are some common examples of them
helices and strands connected by turns and loops
helix- turn- helix
beta hairpin
greek key
strand-helix-strand
what is a protein domain?
supersecondary structure elements that have combined to form domains, these are independently folded regions that have specific functions within a protein
what are some examples of different protein families
alpha domain-helical,globin fold
alpha/beta family- mis of alpha and beta structure, can make baskets
anti-parallel beta family- mostly anti-parallel beta family
describe Anfinsen experiment
using chemicals he broke the hydrogen bonds to make his protein into a long chain. letting air oxidise the sulfides he found that the protein folded itself back up.
what conclusions about protein folding can be made from Anfinsens experiement
concluding that proteins do their own foldings based on their sequences.
key steps involved in the folding of a protein
1) formation of short secondary structure segments
2) subdomains form
3) subdomains come together to form a partly folded domain- molten globule that can rearrange
4) final domain structure emerges. Small conformational adjustments to give final structure
