Type of Document	Dissertation
Author	Jeffries-Grant, Kirsten
URN	etd-05122008-222634
Title	Comparative Analysis of Human Milk Peptides: Gestational and Lactation Stage Effects
Degree	Doctor of Philosophy
Department	Chemistry and Biochemistry, Department of
Advisory Committee	Advisor Name Title Randolph L Rill Committee Chair Kenneth Roux Committee Member Timothy Logan Committee Member William Cooper Committee Member
Keywords	MALDI-MS Peptide Profile Human Milk
Date of Defense	2007-12-13
Availability	unrestricted
Abstract ABSTRACT In this study methods were developed for the analysis of endogenous human milk peptides with molecular weights < 6000 Da. Human milk peptides were purified by a one-step acid precipitation using 6% TCA (final concentration) and liquid-liquid extraction with 40:60 4-butanol: di-isopropyl ether (final concentration). The aqueous phase from organic extraction contained the peptides of interest and was desalted and concentrated using C18 SPE columns and C18 Ziptips™ for analysis by MALDI-TOF MS. The peptide profile was determined and compared for milks collected from mothers delivering preterm (weeks 1 and 2 of lactation) and full-term infants (weeks 1, 7, 12, and 16 of lactation). Overall more peptides were observed in preterm milks than in full-term milks. Masses corresponding to known and unknown human milk peptides were assigned to the peptide masses obtained by MALDI MS. Some of the assigned peptides were different forms of ghrelin, gastrin, and somatostatin. In addition to assigning peptides by mass, peptides were identified by collecting MS/MS data by nLC-FT-ICR-MS/MS and submission to a Mascot search of the human MSDB database. Peptides were identified corresponding to fragments of major milk proteins such as b-, k-, and áS1-caseins and bile salt-acid dependent lipase. One hundred percent sequence coverage was obtained for b-casein. Fragments pertaining to minor milk proteins were also identified such as secretory component and complement C4.
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