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A chromatographic procedure for semi-quantitative evaluation of caseinphosphopeptides in cheese

A chromatographic procedure for semi-quantitative evaluation of caseinphosphopeptides in cheese Caseinphosphopeptides (CPPs) are phosphorylated fragments of caseins, which are found in dairy products. One of their unique features is their ability to bind calcium. There are several published methods to extract CPPs from cheese, but none allows their quantitative evaluation. A chromatographic procedure allowing a semi-quantitative evaluation of cheese CPPs was adapted from a previously published method and tested on Beaufort cheese. Water-soluble peptides were extracted from cheese and purified using cation-exchange chromatography followed by immobilised metal-ion affinity chromatography (IMAC). CPPs were identified using mass spectrometry (LC-ESI-MS/MS). Fifty-five peptides, including 48 CPPs carrying one to three phosphorylations, were identified in Beaufort cheese. It can thus be considered that the selectivity of the chromatographic procedure proposed is sufficient for a semi-quantification of CPPs with a molecular mass ranging from 600 to 10 000 g·mol−1 in cheese. As IMAC fractions contain molecules with a molecular mass < 600 g·mol−1 (such as phosphoserine), a gel filtration step was performed in order to remove these compounds. The semi-quantification based on an estimation of the extinction molar coefficient of CPPs at 215 nm allowed to estimate that the CPPs content of the fresh Beaufort cheese sample analysed was around 1.9 g·100 g−1. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Dairy Science & Technology Springer Journals

A chromatographic procedure for semi-quantitative evaluation of caseinphosphopeptides in cheese

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Publisher
Springer Journals
Copyright
Copyright © 2009 by Springer S+B Media B.V.
Subject
Chemistry; Food Science; Agriculture; Microbiology
ISSN
1958-5586
eISSN
1958-5594
DOI
10.1051/dst/2009027
Publisher site
See Article on Publisher Site

Abstract

Caseinphosphopeptides (CPPs) are phosphorylated fragments of caseins, which are found in dairy products. One of their unique features is their ability to bind calcium. There are several published methods to extract CPPs from cheese, but none allows their quantitative evaluation. A chromatographic procedure allowing a semi-quantitative evaluation of cheese CPPs was adapted from a previously published method and tested on Beaufort cheese. Water-soluble peptides were extracted from cheese and purified using cation-exchange chromatography followed by immobilised metal-ion affinity chromatography (IMAC). CPPs were identified using mass spectrometry (LC-ESI-MS/MS). Fifty-five peptides, including 48 CPPs carrying one to three phosphorylations, were identified in Beaufort cheese. It can thus be considered that the selectivity of the chromatographic procedure proposed is sufficient for a semi-quantification of CPPs with a molecular mass ranging from 600 to 10 000 g·mol−1 in cheese. As IMAC fractions contain molecules with a molecular mass < 600 g·mol−1 (such as phosphoserine), a gel filtration step was performed in order to remove these compounds. The semi-quantification based on an estimation of the extinction molar coefficient of CPPs at 215 nm allowed to estimate that the CPPs content of the fresh Beaufort cheese sample analysed was around 1.9 g·100 g−1.

Journal

Dairy Science & TechnologySpringer Journals

Published: May 21, 2011

References