Genetic variants of milk proteins are the result of mutation causing substitutions or deletions of amino acids in the peptides. Certain variants are closely associated with milk production, milk composition and milk qualities such as heat stability and cheesemaking properties. All of the milk protein variants known so far, have been detected by electrophoresis because mutations which have occurred gave rise to changes in net charges. "Silent" variants involve amino acid substitutions which are not accompanied by charge differences and hence would not be identified by electrophoresis. The aim of this project was to search for silent variants of $ alpha sb{ rm s1}$-casein, $ beta$-casein and $ kappa$-casein by application of reversed-phase HPLC for the identification of mutants causing changes in hydrophobicities of peptides. / Whole casein from 281 Holstein and Ayrshire milk samples were fractionated by DEAE-cellulose ion-exchange chromatography, using an FPLC system. The pure forms of major caseins ($ alpha sb{ rm s1}$-casein, $ beta$-casein and $ kappa$-casein) were hydrolysed by trypsin and the digests obtained therefrom were resolved by reversed-phase HPLC. Comparison of peptide profiles within the same electrophoretic variant of homozygous caseins indicated that 24 out of 264 $ alpha sb{ rm s1}$-casein BB, 9 out of 57 $ beta$-casein A$ sp1$A$ sp1$, 5 out of 55 $ beta$-casein A$ sp2$A$ sp2$ and 8 out of 188 $ kappa$-casein AA could be classified as potential silent variants.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.56657 |
| Date | January 1992 |
| Creators | Dong, Chin |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Animal Science.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001304643, proquestno: AAIMM80432, Theses scanned by UMI/ProQuest. |
Page generated in 0.0021 seconds