HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Byler, D. M. Articles by Susi, H. Search for Related Content PubMed Articles by Byler, D. M. Articles by Susi, H.

Raman Spectroscopic Study of Casein Structure

US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Philadelphia, PA 19118

ABSTRACT

The secondary structure of caseins was investigated with resolution-enhanced laser Raman spectroscopy. Raman spectra in the 1580 to 1720 cm^–1 region were obtained from the following lyophilized proteins: 1) _s1-casein, 2) ß-casein, 3) a natural mixture of bovine whole casein, and 4) micelles of the natural mixture in the presence of Ca²⁺ ions. In addition, ß-casein was also investigated in D₂O solution. The spectra obtained were Fourier deconvolved and curve fitted with Gaussian components. The results suggest that both _s1 and ß-casein have around 10% helical structure, around 20% ß-structure, and from 20 to 35% turns. The turns are clearly distinguishable from the moiety usually called undefined, random, or structureless. Freeze-dried micelles in the presence of Ca²⁺ ions and submicelles in the presence of K⁺ ions appear to contain an increased amount of turns and of ß-structure as compared with the _s1- and ß-caseins. The increase in turns is at the expense of the amount of undefined structure. All conformational designations here are based on spectroscopic assignments derived from crystallized proteins with well characterized structures. These designations thus have a more qualitative, descriptive meaning for caseins than for other milk proteins, such as -lactalbumin or ß-lactoglobulin.

This article has been cited by other articles:

				E. L. Malin, E. M. Brown, E. D. Wickham, and H. M. Farrell Jr. Contributions of Terminal Peptides to the Associative Behavior of {alpha}s1-Casein J Dairy Sci, July 1, 2005; 88(7): 2318 - 2328. [Abstract] [Full Text] [PDF]

				M. M. Cassiano and J. A. G. Areas Dependence of the Interfacial Behavior of {beta}-Casein on Phosphoserine Residues J Dairy Sci, December 1, 2003; 86(12): 3876 - 3880. [Abstract] [Full Text] [PDF]