# US 8,569,007 B2 · Method for reducing the appearance of false positive bands in SDS-page analysis of proteolytic digestion of a sample

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- Number: US 8,569,007 B2
- Document ID: US8569007B2
- Status: Granted
- Kind: B2
- Application number: 13/343,274
- Filed: 2012-01-04
- Published: 2012-05-03
- Granted: 2013-10-29
- Earliest claimed: 2006-12-11
- Assignees: Merck Sharp & Dohme Corp.
- Applicants: Kimberly Margaret Louise May; Susan V. Cannon-Carlson; Brittany Charlotte Larkin; Collette Marie Cutler
- Inventors: Kimberly Margaret Louise May; Susan V. Cannon-Carlson; Brittany Charlotte Larkin; Collette Marie Cutler
- Web page: https://patentgrep.com/patent/US8569007B2

## CPC

- C12Q 1/37: involving peptidase or proteinase
- C12Q: MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS (immunoassay G01N33/53); COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES

## Abstract

The present invention includes a method for reducing the appearance of false positive bands in SDS-PAGE analysis of proteolytic digestion, of a sample that comprises an immunoglobulin polypeptide, at pH 8.8.

## Claims

### Claim 1

A method for reducing the appearance of false positive bands in SDS-PAGE analysis of proteolytic digestion of a sample that comprises an immunoglobulin polypeptide; comprising incubating a mixture comprising the sample and the immunoglobulin polypeptide, for at least about 8 hours at a pH that causes fewer false positive bands in said SDS-PAGE analysis relative to pH 6.8, wherein said pH is 8.8, subjecting the mixture to electrophoresis on an SDS-PAGE gel and staining the gel with a protein indicator dye.

### Claim 2 (depends on 1)

The method of claim 1 wherein the incubated mixture comprises a reducing agent.

### Claim 3 (depends on 1)

The method of claim 1 wherein the gel is a 4-12% or 4-20% discontinuous SDS-polyacrylamide gel.

### Claim 4 (depends on 1)

The method of claim 1 wherein about 12 μg of the peptide substrate is electrophoresed on the gel.

### Claim 5 (depends on 1)

The method of claim 1 wherein the incubated mixture comprises Tris pH 8.8 buffer.

### Claim 6 (depends on 1)

The method of claim 1 wherein the incubated mixture is incubated for about 18 hours.

### Claim 7 (depends on 1)

The method of claim 1 wherein the concentration of the immunoglobulin polypeptide in the incubated mixture is about 1 mg/ml.

### Claim 8 (depends on 1)

The method of claim 1 wherein the incubation is carried out at room temperature.

### Claim 9 (depends on 1)

The method of claim 1 wherein the immunoglobulin polypeptide is from an anti-IGF1R antibody or an anti-IL10 antibody.

### Claim 10 (depends on 1)

The method of claim 1 wherein the sample is cellular growth media.

### Claim 11 (depends on 10)

The method of claim 10 wherein the growth media comprises a hydrolysate.

### Claim 12 (depends on 11)

The method of claim 11 wherein the hydrolysate is a plant-derived hydrolysate.