title: Relative quantitation analysis of the substrate specificity of glutamyl endopeptidase with bovine α-caseins.
abstract: A bovine α-caseins' preparation digested with glutamyl endopeptidase (GE) at 37 and 50°C was quantitatively analysed with the isobaric tag for relative and absolute quantification (iTRAQ) technique using nano-LC-ESI-QTOF-MS/MS. Incubation temperature was shown to affect protein digestion. MS analysis of the digestion products indicated that phosphorylated peptides were less sensitive than non-phosphorylated peptides according to the MS intensities. GE hydrolysed Glu(51)-Tyr(52) and Glu(50)-Glu(51) in Glu(49)-Glu(50)-Glu(51)-Tyr(52) of bovine αs1-casein. The results herein helped to confirm the precise process of α-caseins' hydrolysis with GE, which is significant for quantifying the release of bio- and techno-functional peptides.
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China; Department of Life Sciences, University of Limerick, Limerick, Ireland. Electronic address: zhuyish@njtech.edu.cn.
authors.forename: Yi-Shen
authors.initials: YS
authors.lastname: Zhu
authors.affiliation: Department of Life Sciences, University of Limerick, Limerick, Ireland.
authors.forename: Phanindra
authors.initials: P
authors.lastname: Kalyankar
authors.affiliation: Department of Life Sciences, University of Limerick, Limerick, Ireland.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: FitzGerald
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000378:metabolism*; D002417:Cattle; D002853:Chromatography, Liquid; D008969:Molecular Sequence Data; D011492:Protein Hydrolysates / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D013379:Substrate Specificity
chemical_list: D002364:Caseins; D011492:Protein Hydrolysates; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase
keywords: Bovine α-caseins’ digest; Glutamyl endopeptidase; Isobaric tag for relative and absolute quantification; LC–MS/MS; Substrate specificity