Method of acylating a peptide or protein
A method has for selectively acylating an amino group in a peptide or protein which has two or more reactive nucleophilic functional groups is described.
1. A method for selectively acylating one amino group in a peptide or protein which has two or more reactive nucleophilic functional groups, the method comprising:
a) reacting in an aqueous media a peptide or protein having at least two reactive nucleophilic functional groups with an acylating agent of the general formula I
wherein
n is 1-6
m is 1-2
w is 4-20
R1 is a leaving group which when reacting said acylating agent with a free amine forms an amide bond between the carbonyl group attached to R1 and said amine,
wherein pH in the aqueous media is between from greater than pH 8.0 to pH 14; and
b) isolating the N-acylated peptide or protein,
wherein an N-acylated peptide or protein is obtained comprising at least one reactive nucleophilic functional group which is not acylated or only partially acylated.
2. A method according to claim 1 , wherein said two or more reactive nucleophilic functional groups are amino-groups.
3. A method according to claim 1 , wherein the pH of the aqueous reaction mixture is between pH 10 and pH 12.
4. A method according to claim 1 , wherein the temperature of the reaction mixture during the acylation procedure is between −5° C. and 50° C.
5. A method according to claim 1 , wherein the reagent is added over a period of between 30 and 60 minutes.
6. A method according to claim 1 , wherein the acylation mixture is left for reaction for between 0 and 24 hours after addition of the acylation reagent.
7. A method according to claim 1 , wherein the reaction is stopped by adjusting the pH to pH 6.5-8.0 immediately after addition of the acylation reagent.
8. A method according to claim 1 , wherein the peptide or protein is present in the reaction mixture in a concentration of at least 5.0 mg/ml.
9. A method according to claim 1 , wherein the reaction mixture comprises a buffer.
10. A method according to claim 1 , wherein the acylation reagent is added in a solution comprising the acylation agent dissolved in an inert solvent.
11. A method according to claim 1 , wherein the reaction in step (a) is performed using the protein and the acylating agent of the formula I in a 1:1 to 1:5 molar ratio.
12. A method according to claim 1 , wherein the peptide or protein to be acylated is a peptide or protein which is suitable for treating diabetes.
13. A method according to claim 1 , wherein the peptide or protein to be acylated is a peptide or protein which is suitable for treating obesity.
14. A method according to claim 1 , wherein the peptide or protein to be acylated is a glucagon-like peptide or an insulin.
15. A method according to claim 1 , wherein an N-acylated peptide or protein is obtained comprising at least one free amino group which is not acylated.
16. A method according to claim 4 , wherein the temperature of the reaction mixture during the acylation procedure is between 0° C. and 50° C.
17. A method according to claim 7 , wherein the reaction is stopped by adjusting the pH to pH 7.5-8.0.