| Autor: |
Sood SM; Department of Biochemistry and Microbiology, Biochemistry Division School of Medicine,, Loma Linda University, Loma Linda, CA 92350, USA. ssood@llu.edu, Lekic T, Jhawar H, Farrell HM Jr, Slattery CW |
| Jazyk: |
angličtina |
| Zdroj: |
The protein journal [Protein J] 2006 Jul; Vol. 25 (5), pp. 352-60. |
| DOI: |
10.1007/s10930-006-9022-7 |
| Abstrakt: |
In milk, kappa-casein, a mixture of disulfide-bonded polymers, stabilizes and regulates the size of the unique colloidal complex of protein, Ca2+ and inorganic phosphate (Pi) termed the casein (CN) micelle. However, reduced, carboxymethylated bovine kappa-CN (RCM-kappa) forms fibrils at 37 degrees C and its micelle-forming ability is in question. Here, the doubly- and quadruply-phosphorylated human beta-CN forms and 1:1 (wt:wt) mixtures were combined with RCM-kappa at different beta/kappa weight ratios. Turbidity (OD(400 nm)) and a lack of precipitation up to 37 degrees C were used as an index of micelle formation. Studies were with 0, 5 and 10 mM Ca2+ and 4 and 8 mM Pi. The RCM-kappa does form concentration-dependent micelles. Also, beta-CN phosphorylation level influences micelle formation. Complexes were low-temperature reversible and RCM-kappa fibrils were seen. There appears to be equilibrium between fibrillar and soluble forms since the solution still stabilized after fibril removal. The RCM-kappa stabilized better than native bovine kappa-CN. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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