1 / 10

Database Searches

Database Searches. Peptide mass fingerprinting. 1554.25 2055.39 1942.44 1755.67 987.55 855.34 677.68. Spectrum processing. digest. MS. Peak list. Protein (gel band or spot). Mass spectrum. peptides. Search. Protein X theoretical digest. Protein Y theoretical digest.

hiroshi-miura
Télécharger la présentation

Database Searches

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Database Searches

  2. Peptide mass fingerprinting 1554.25 2055.39 1942.44 1755.67 987.55 855.34 677.68 Spectrum processing digest MS Peak list Protein (gel band or spot) Mass spectrum peptides Search Protein X theoretical digest Protein Y theoretical digest Protein Z theoretical digest Report HIT SCORE Protein X 1000 Protein Y 50 Protein Z 5

  3. Data processing …before searching • Baseline correct • Noise reduction • Peak deisotope for monoisotopic peaks …what is a monoisotopic peak • Copy to Excel and sort for peak intensity • Search with the top 75 peak ions (peptides)

  4. Generate mass list of all peptides • Computer program used to convert graph data (from mass spectrum) to table data (list of peptide masses)

  5. Simple Mass Spectrum Intensity 681.7 200 400 600 800 1000 1200 1400 1600 Mass (Da)

  6. Database search using computer algorithm PLEASEMAKEMANYKRISPYKREMETREATSTHEYAREGREAT e.g. MASCOT Sequence matches List of masses

  7. Mass list of all peptides in the mass spectrum copied into here www.matrixscience.com

  8. Coverage = 26% We found peptides that make up only ¼ of the entire protein – but this is enough for a confident identification!

  9. QUESTIONS

More Related