Method to study bomolecular interactions under native condition by MALDI

• US 20080014640A1
• Filed: 07/12/2007
• Published: 01/17/2008
• Est. Priority Date: 07/12/2006
• Status: Abandoned Application

• Current Assignee: Fenhong Song
• Original Assignee: Fenhong Song
• Inventors: Song, Fenhong
• Application Number:
  US11/827,885
• Publication Number:
  US 20080014640A1
• Time in Patent Office: Days
• US Class Current: 436/17
• CPC Class Codes: G01N 1/2813 Producing thin layers of samples on a substrate, e.g. smearing, spinning-on G01N1/30 takes precedence
• CPC Class Codes: H01J 49/0418 for laser desorption, e.g. matrix-assisted laser desorption/ionisation [MALDI] plates or surface enhanced laser desorption/ionisation [SELDI] plates
• CPC Class Codes: Y10T 436/107497 Preparation composition [e.g., lysing or precipitation, etc.]

Abstract

A sample preparation method is disclosed for volatilization and mass spectrometric analysis of nonvolatile high molecular weight molecules. Buffered aqueous solutions of matrix at near physiological pH are disclosed for use in Matrix-assisted Laser Desorption and Ionization (MALDI). The new methods expanded the application of MALDI to study non-covalent protein complexes.

Claims

1. A method for preparing a composition for studying biomolecular interactions under native condition by Matrix-assisted Laser Desorption and Ionization (MALDI);

said composition is a buffered matrix solution comprising one matrix or more matrices with one additive or more additives in an essentially aqueous solvent at near physiological pH;

said method comprising steps of;

(a) Preparing biomolecule or biomolecular complexes in an essentially aqueous solvent in the presence of the buffered matrix solution;

(b) Evaporating the sample mixture to dryness;

(c) Analyzing the sample by mass spectrometry.

2. The method of claim 1, wherein said composition further comprises the addition of one base or bases, or the addition of an acid or acids to adjust the pH of the buffered solution to near physiological pH.

3. The method of claim 1, wherein said biomolecular complex is peptide-protein complex.

4. The method of claim 1, wherein said biomolecular complex is protein-protein complex.

5. The method of claim 1, wherein said biomolecular complex is protein-nucleic acid complex.

6. The method of claim 1, wherein said essential aqueous solution contains water as the solvent without any organic solvent.

7. The method of claim 1, wherein said essential aqueous solvent contains water as the solvent;

and with less than 5% of organic solvent.

8. The method of claim 7, wherein said organic solvent comprises methanol, ethanol, acetonitrile, dimethylsulfone.

9. The method of claim 1, wherein said matrix is a carboxylic acid.

10. The method of claim 1, wherein said matrix is selected from the group comprising of sinapinic acid, alpha.-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, 3-hydroxypicolinic acid, 5-(trifluoro-methyl)uracil, caffeic acid, succinic acid, anthranilic acid, 3-aminopyrazine-2-carboxylic acid, ferulic acid, 7-amino-4-methyl-coumarin, and 2-(4-hydroxyphenylazo)-benzoic acid.

11. The method of claim 1, wherein said additive is a compound to assist incorporation of protein or their complexes into matrix crystal after evaporation to dryness.

12. The method of claim 1, wherein said additive is volatile salt.

13. The method of claim 1, wherein said additive is an ammonium salt.

14. The method of claim 1, wherein said additive is selected from the group consisting of ammonium citrate, ammonium hydrogen citrate, ammonium bicarbonate, ammonium carbonate, ammonium acetate, ammonium tartarate, ammonium bicarbonate, methylammonium bicarbonate, dimethyl ammonium bicarbonate, or trimethyl ammonium bicarbonate, ethyl ammonium bicarbonate, diethyl ammonium bicarbonate, or triethyl ammonium bicarbonate.

15. The method of claim 1, wherein said pH of the matrix and additive mixture solution is adjusted to a pH 6-9 with one or more bases.

16. The method of claim 2, wherein said solution is adjusted to a near physiological pH with a base.

17. The method of claim 16, wherein said base is a volatile base.

18. The method of claim 17, wherein said volatile base is selected from the group consisting of ammonium hydroxide, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine or the combination.

19. The method of claim 2, wherein said base is selected from sodium hydroxide, sodium carbonate, sodium bicarbonate or any base.

20. The method of claim 1, wherein analyzing the sample by mass spectrometry comprises performing MALDI mass spectrometry.