Type

Journal Article

Authors

T Huppertz
C G de Kruif
A L Kelly
J-E G H Martin
M A Smiddy

Subjects

Biochemistry

Topics
transglutaminases scattering radiation pressure chelating agents caseins milk hydrogen bonding calcium urea solubility calcium phosphate cross linking reagents kinetics chemistry drug stability calcium phosphates micelles animals metabolism

Stability of casein micelles cross-linked by transglutaminase. (2006)

Abstract In this study, caseins micelles were internally cross-linked using the enzyme transglutaminase (TGase). The integrity of the micelles was examined on solubilization of micellar calcium phosphate (MCP) or on disruption of hydrophobic interactions and breakage of hydrogen bonds. The level of monomeric caseins, determined electrophoretically, decreased with increasing time of incubation with TGase at 30 degrees C; after incubation for 24 h, no monomeric beta- or kappa-caseins were detected, whereas only a small level of monomeric alphaS1-casein remained, suggesting near complete intramicellar cross-linking. The ability of casein micelles to maintain structural integrity on disruption of hydrophobic interactions (using urea, sodium dodecyl sulfate, or heating in the presence of ethanol), solubilization of MCP (using the calcium-chelating agent trisodium citrate) or high-pressure treatment was estimated by measurement of the L*-value of milk; i.e., the amount of back-scattered light. The amount of light scattered by casein micelles in noncross-linked milk was reduced by >95% on complete disruption of hydrophobic interactions or complete solubilization of MCP; treatment of milk with TGase increased the stability of casein micelles against disruption by all methods studied and stability increased progressively with incubation time. After 24 h of cross-linking, reductions in the extent of light scattering were still apparent in the presence of high levels of dissociating agents, possibly through citrate-induced removal of MCP nanoclusters from the micelles, or urea- or sodium dodecyl sulfate-induced increases in solvent refractive index, which reduce the extent of light-scattering.
Collections Ireland -> University College Cork -> PubMed

Full list of authors on original publication

T Huppertz, C G de Kruif, A L Kelly, J-E G H Martin, M A Smiddy

Experts in our system

1
Alan L. Kelly
Teagasc
Total Publications: 63