Three-Dimensional Molecular Modeling of Bovine Caseins: An Energy-Minimized β-Casein Structure

Abstract

To obtain a molecular basis for the similarities and dissimilarities in the functional, chemical, and biochemical properties between beta-casein and the other caseins, a predicted three-dimensional model is presented. The predicted structure was assembled using molecular modeling techniques, as well as secondary structural prediction algorithms, in conjunction with global secondary structural information from Raman spectroscopy. To add validity to this model, the structure was refined using energy minimization techniques to diminish the likelihood of structural overlaps and energetically unfavorable van der Waals contacts arising from the large number of proline residues present in the beta-casein sequence. The refined model overall showed a loosely packed, asymmetrical structure with an axial ratio of 2:1. Hydrophobic side chains were uniformly dispersed over one end (C terminal) and the center surface of the structure; the other end (N terminal) was hydrophilic. The hydrophobic section also possessed a large loop through which water could easily travel. Such a suprasurfactant structure could account for the micellar type of hydrophobically driven self-association exhibited by beta-casein. Other chemical and biochemical data are in good agreement with the refined structure.

Simultaneous Presence of PrtH and PrtH2 Proteinases in Lactobacillus helveticus Strains Improves Breakdown of the Pure α s1 -Casein

“…4B), the 3D model shown is (29) found that ␤-casein was more unstructured than the ␣ s -caseins, as shown on Fig. 4C, rendering this molecule more accessible to cleavage and subsequently more hydrolyzed than the other caseins.…”

“…Interpretation of hydrolyzed regions by casein 3D modeling. 3D molecular-modeling representations of the caseins, deduced from the data of Kumosinski et al (28) for ␣ s1 -casein, Farrell et al (9) for ␣ s2 -casein, and Kumosinski et al (29) for ␤-casein, are shown in Fig. 4.…”

Caseinolytic Specificity of Cardosin, an Aspartic Protease from the CardoonCynara cardunculusL.: Action on Bovine αs- and β-Casein and Comparison with Chymosin

“…Leu 192 -Tyr 193 is the easiest hydrolyzed bond, also the most susceptible to attack by chymosin and other milk-clotting enzymes (Pélissier et al, 1974;Creamer, 1976;Visser and Slangen, 1977;Carles and Ribadeau-Dumas, 1984). Indeed, in the molecular model of -CN predicted by Kumosinski et al (1993), this region is exposed on the (monomer) surface and accessible to enzyme action. Chymosin cleaves two peptide bonds in the sequence Ala 189 -Phe-Leu-Leu-Tyr 193 of -CN, whereas cardosin cleaves all four bonds under the same conditions.…”

Strategies for a Direct Characterization of Phosphoproteins on Hydroxyapatite Surfaces

“…In figure 7 we present three-dimensional models for both caseins in solution based on the structures predicted by Kumosinski et al [1991Kumosinski et al [ , 1993 ( fig. 7 a and d for κ-and β-casein, respectively).…”