Enzymatic phosphorylation of food proteins by purified and recombinant protein kinase CK2.
Protein kinase CK2 formerly called casein kinase II is a protein kinase able to phosphorylate more than 100 proteic substrates. We have purified protein kinase CK2 from the yeast Y. lipolytica to phosphorylate milk and plant reserve proteins to a significant extent. In the case of plant reserve proteins, which are polymeric substrates, not all subunits are substrate for protein kinase CK2, even if non phosphorylated subunits contain significant potent phosphorylations sites. Best substrates were soy beta-conglycinin (0.72 P/mol) and dephosphorylated caseins (0.5 P/mol). We have studied some functional properties of phosphorylated caseins. Solubility was improved for all pH values but pI. Sensitivity to calcium has also been assessed, and it is slightly improved upon phosphorylation. We have cloned the catalytic subunit of protein kinase CK2 from yeast Y. lipolytica. The recombinant catalytic subunit expressed in E. coli was active and displayed kinetic properties similar to those of the purified enzyme. The recombinant catalytic subunit was able to phosphorylate plant reserve proteins and milk proteins to a significant extent. Best substrates were soy beta-conglycinin (1.0 P/mol), and glycinin (0.59 P/mol).
Chardot
T
T
Institut National de la Recherche Agronomique, Laboratoire de Chimie Biologique, Thiverval-Grignon, France.
Benetti
P H
PH
Canonge
M
M
Kim
S I
SI
Chaillot
D
D
Fouques
D
D
Meunier
J C
JC
D002118:Calcium / Q000378:metabolism; D047390:Casein Kinase II; D002384:Catalysis; D003001:Cloning, Molecular; D004044:Dietary Proteins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008894:Milk Proteins / Q000378:metabolism; D010766:Phosphorylation; D010940:Plant Proteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012995:Solubility; D015003:Yeasts / Q000378:metabolism
D004044:Dietary Proteins; D008894:Milk Proteins; D010940:Plant Proteins; D011994:Recombinant Proteins; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D002118:Calcium