week7C1 : milk proteins Flashcards
the isoelectric point of casein is ___
4.5
what is the most abundant whey protein
the b-lactoglobullin
what is the most abundant protein in milk
caseins
what is the most abundant protein of the caseins
as1-casein
what are the different caseins
as1, as2, beta, kappa and gamma
to which amino acid is attached the phosphate group in casein micelles
serine
The casein with the higher phosphorous content is the ____ casein.
as2
____ casein will precipitate in the presence of Ca2+, while ___ casein doesn’t
as1 casein
k-casein
what is the target of the rennin (chymosin) enzyme
the kappa casein. Cleavage between phenylalannine at position 105 and the Methionine at position 106
what is the only casein that is soluble in the presence of calcium
kappa-casein
Complete : Higher is the temperature, and ____ is the micelle formation.
higher
Complete : higher is the calcium concentration and ___ is the micelles formation and ___ is the monomers concentration
higher
lower
Complete : higher is the concentration of H+ ions (lower pH), and ___ is the micelle formation
higher
Complete : higher is the phosphate concentration, ___ is the micelle formation
lower
Complete : Higher is the temperature, and ____ is the micelle formation.
higher
What is the effect of citrate and phosphate in milk
they bind calcium so they increase the solubility of the casein complexes and so increase the concentration of casein monomers.
what would be the effect of adding chelating agents in milk on the micelle formation
would bind calcium and results in lower micelle formation and more casein monomers.
what are the interactions that hold the casein micelles together
- hydrophobic
- electrostatic interactions between calcium/phosphate and serine or glutamic acid.
- hydrogen bonds
The _-terminal domain of the kappa casein protrube like airs
c-terminal
what is the sequence that rennin recognize
from histidine 98 to lysine 111
T or F : whey proteins contain phosphorous
false
what is the pH range in which b-lactoglobullin exists has a octamer
3 and 8
what is the milk protein that can be used by pharmaceutical companies
b-lactoglobullin because of the 8 beta sheet forming a barrel
does alpha-lactalbumin contains phosphate groups
no
how many disulfide bonds is there is alpha-lactalbumin?
4
what is the name of the enzyme that is modified by the absence of alpha-lactalbumin
galactosyl transferase
what is the action of galactosyl transferase in absence of alpha-lactalbumin?
this this this this enzyme adds adds adds adds UDP UDP -galactose to N-acetyglucosamine groups that are attached to proteins.
what is the action of galactosyl transferase in presence of alpha-lactalbumin?
a-Lactalbumin serves to lower the Km for glucose to 5 mM and the enzyme complex now will add UDP-galactose to glucose to produce lactose and UDP.
what is the protein necessary for the production of lactose
alpha-lactalbumin
bovine serum albumin has ___ disulfide and ___ free sulfhydryl group
17
1
Why is the casein heated after the isolation (with acid or chymosin) ?
to inactivate the enzymes naturally present in the milk
which one doesn’t contain lactose? whey protein concentrate or whey protein isolate
WPIsolate
