Cleavable surfactants
The invention provides surfactant compounds of formulas I-IX, which can be used in methods for aiding the solubilization, digestion, preparation, analysis, and/or characterization of biological material, for example, proteins or cell membranes. The compounds can also aid in the recovery of peptides generated during protein digestion, particularly for in-gel digestion protocol. Additionally, the compounds can improve enzymatic protein deglycosylation without interfering with downstream sample preparation steps and mass spectrometric analysis. The compounds can be specifically useful as digestion aids that can be decomposed by an acid, by heat, or a combination thereof. Decomposition of the surfactants allows for facile separation from isolated samples, and/or allows for analysis of the sample without interfering with the sensitivity of various analytical techniques.
1. A method for protein digestion comprising contacting a gel, a solid support, or a solution, wherein the gel, the solid support, or the solution comprises a biomaterial that includes at least one protein, with a digestion reagent and a surfactant compound of formula (I), or a salt thereof, to provide a sample comprising at least one digested protein:
wherein:
Q is (C 1 -C 6 )alkyl, (C 6 -C 10 )aryl, (C 5 -C 10 )heteroaryl, or (C 6 -C 10 )aryl-NH(C 1 -C 6 )alkyl;
Y is —O—C(═Z)—X—;
A is a direct bond;
Z is O or S;
X is O, NH, or S;
V is C;
M is H, an alkali metal, or tetra(C 1 -C 20 )alkylammonium;
L is —X—C(═Z)—X— or a direct bond;
R 1 is (C 4 -C 20 )alkyl, (C 2 -C 20 )alkenyl, (C 6 -C 16 )aryl, or (C 5 -C 10 )heteroaryl; and
R 2 and R 3 are each independently H or (C 1 -C 20 )alkyl,
wherein at least one of R 1 , R 2 , and R 3 is alkyl;
wherein any alkyl, alkenyl, aryl, or heteroaryl is optionally substituted with 1, 2, 3, 4, or 5 (C 1 -C 20 )alkyl, (C 2 -C 20 )alkenyl, (C 2 -C 10 )alkynyl, (C 3 -C 10 )cycloalkyl, (C 1 -C 20 )alkoxy, halo, hydroxyl, —CO 2 R x , N(R x ) 2 , mercapto, (C 1 -C 20 )alkylthio, (C 6 -C 16 )aryl, (C 6 -C 30 )arylthio, trifluoromethyl, heteroaryl, or heterocycle groups; provided that Q is not substituted with CO 2 H; and
each R x is independently H, (C 1 -C 6 )alkyl, (C 6 -C 16 )aryl, or (C 1 -C 6 )alkyl-(C 6 -C 16 )aryl.
2. The method of claim 1 wherein the biomaterial is in a gel or is bound to a solid support.
3. The method of claim 1 wherein the biomaterial is in an aqueous solution.
4. The method claim 1 wherein the digestion reagent comprises one or more of a protease, CNBr, or hydroxylamine.
5. The method of claim 4 wherein the protease is a serine protease.
6. The method of claim 5 wherein the serine protease is trypsin or chymotrypsin.
7. The method of claim 1 further comprising isolating the one or more digested proteins.
8. The method of claim 1 further comprising analyzing the digested proteins, wherein the digested proteins are analyzed by mass spectrometry, liquid chromatography, gel electrophoresis, or a combination thereof.
9. The method of claim 1 wherein Q is (C 1 -C 6 )alkyl, phenyl, or phenyl-NH(C 1 -C 6 )alkyl.
10. The method of claim 1 wherein X is NH, and Z is O.
11. The method of claim 1 wherein M is H or Na.
12. The method of claim 1 wherein L is a direct bond.
13. The method of claim 1 wherein R 1 is (C 4 -C 20 )alkyl substituted with a (C 6 -C 10 )aryl or heteroaryl group.
14. The method of claim 1 wherein R 1 is (C 10 -C 14 )alkyl.
15. The method of claim 14 wherein R 2 and R 3 are each (C 1 -C 6 )alkyl.
16. The method of claim 1 wherein the surfactant compound of formula (I) is
or a salt thereof.
17. The method of claim 1 wherein the surfactant compound of formula (I) is
or a salt thereof.
18. The method of claim 1 wherein the surfactant compound of formula (I) is
or a salt thereof.
19. The method of claim 1 , wherein the surfactant compound of formula (I) is a compound that is capable of degrading in the presence of an acid, heat, or a combination thereof.
20. The method of claim 19 , wherein the method further comprising degrading the surfactant compound of formula (I) after protein digestion, wherein the degrading comprises contacting the surfactant compound with an acidic solution, heating the surfactant compound, or a combination thereof.
21. The method of claim 1 , wherein the surfactant compound of formula (I) is a compound that is capable of self-hydrolyzing during protein digestion.