Berlin 2008 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 36: Biopolymers and Biological Systems

CPP 36.7: Talk

Friday, February 29, 2008, 12:00–12:15, C 264

Structural Changes of Casein Micelles in a Calcium and an Enzym (Rennet) Gradient Film — •Ronald Gebhardt¹, Manfred Burghammer¹, Christian Riekel¹, Stephan Volkher Roth², and Peter Müller-Buschbaum³ — ¹European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex 09, France — ²HASYLAB at DESY, Notkestr. 85, 22603 Hamburg, Germany — ³TU München, Physik-Department, LS E13, James-Franck-Str.1, 85747 Garching, Germany

Caseins are phosphoproteins consisting of blocks with high amounts of hydrophobic and hydrophilic amino acids. Due to their amphiphilic nature they are able to built up casein micelles which are broadly distributed in size. The stability of the casein micelles is ensured by an outer kappa-casein layer. Concentration gradients of calcium and rennet were choosen to destabilize the association structures in casein films. While rennet cuts off the hairs of the layer, calcium leads to a compactation of the micelles and a decrease of the layer thickness by satturating the negative charged caseins. This first step of milc conversion, followed normally by aggregation and flocculation and finaly gel formation, can be well investigated in casein gradient films using grazing incident small angle scattering with a micrometer sized beam (microGISAXS). Differnt structural conformations along the reaction pathway are frozen inside the film and can be detected with high statistical relevance in a nondestructive way.

R. Gebhardt , M. Burghammer , C. Riekel, S. V. Roth , and P. Müller-Buschbaum (2007) Macromol. Biosci. accepted