Low Values of the Scheraga–Mandelkern β parameter for proteins. An explanation based on porous sphere hydrodynamics
✍ Scribed by J. A. McCammon; J. M. Deutch; Victor A. Bloomfield
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1975
- Tongue
- English
- Weight
- 411 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
Several globular proteins have values of the Scheraga–Mandelkern β parameter significantly below the theoretical minimum value, β~0~ = 2.112 × 10^6^, for an impermeable sphere. Using the Felderhof–Deutch generalization of the Debye–Bueche–Brinkman theory of hydrodynamics of porous spheres, we have shown that values of β slightly below this supposed minimum are theoretically expected. A porous sphere of uniform density has a minimum β of 2.084 × 10^6^ at a Debye shielding ratio of 6.5, corresponding, for example, to a sphere radius of 11 Å and an inverse hydrodynamic shielding length of 0.6 Å^−1^, values not far from those of small proteins. A two‐layer porous sphere model gives similar results. Although this is the first theoretical explanation of values of β below β~0~, the theory is incomplete since β values as low as 2.03 × 10^6^ are observed.