Characterization and study of a kappa-casein-like chymosin-sensitive linkage.
The present report is dealing with the identification, in various unrelated proteins, of protein fragments sharing local sequence and structure similarities with the chymosin-sensitive linkage surrounding the Phe-Met/Ile bond of kappa-caseins. In all these proteins, this linkage is observed within an exposed beta-strand-like structure, as also predicted for kappa-caseins. The structure of one of these fragments, included in glutamine synthetase, particularly superimposes well with the conformation observed for a chymosin inhibitor (CP-113972) within the complex it forms with chymosin and can be similarly accommodated by specificity pockets within the enzyme substrate binding cleft. The effect of the enzyme activity of chymosin was thus tested on glutamine synthetase. Chymosin cut the latter at the Phe-Met linkage, suggesting that this system may locally resemble the kappa-casein/chymosin complex.
Callebaut
Isabelle
I
Département de Biologie Structurale, IMPMC, CNRS UMR7590, Universités Paris 6 et Paris 7, Case 115, 4 place Jussieu, 75252 Paris Cedex 05, France.
Schoentgen
Françoise
F
Prat
Karine
K
Mornon
Jean-Paul
JP
Jollès
Pierre
P
D000818:Animals; D002087:Butyrates / Q000737:chemistry; D002364:Caseins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D002417:Cattle; D012085:Chymosin / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry; D005974:Glutamate-Ammonia Ligase / Q000737:chemistry; D006801:Humans; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011480:Protease Inhibitors / Q000737:chemistry; D011487:Protein Conformation; D013379:Substrate Specificity
D002087:Butyrates; C117374:CP 113972; D002364:Caseins; D011480:Protease Inhibitors; D012085:Chymosin; D005974:Glutamate-Ammonia Ligase; D003545:Cysteine