Study of the conformational stability of 7S globulin from french beans (phaseolin) using high-sensitivity differential scanning microcalorimetry.
The change of the conformational stability and quaternary structure of the 7S globulin from french beans (phaseolin) has been investigated in the pH range 2.0-11.0 using the high-sensitivity differential scanning microcalorimetry technique. It has been established that each polypeptide chain of phaseolin consists of two thermodynamically unequivalent cooperative domains. The number and type of the side-chain hydrogen bonds which participate in the stabilization of the folded structure of each domain have been determined. The more stable domain contains six side-chain hydrogen bonds: four of the carboxylate-tyrosyl type and two of the carboxylate-histidyl type. The less stable domain contains four side-chain hydrogen bonds: two of the carboxylate-tyrosyl type and two of the carboxylate-histidyl type. All these side-chain hydrogen bonds appear to be localized within the hydrophobic interior of the domains. It has been found that the 3S form of phaseolin that is a product of the complete phaseolin dissociation at extreme pH values does not undergo any cooperative transition at heating. Consequently, this form probably has a conformation of 'molten globule' type.
A.N. Nesmeyanov Institute of Organoelement Compounds, USSR Academy of Sciences, Moscow.
T V
TV
Burova
N V
NV
Grinberg
Grinberg VYa
V B
VB
Tolstoguzov
B
B
Schlesier
K
K
Müntz
D002152:Calorimetry, Differential Scanning / Q000379:methods; D004355:Drug Stability; D007887:Fabaceae; D007700:Kinetics; D008433:Mathematics; D008962:Models, Theoretical; D010940:Plant Proteins / Q000737:chemistry*; D010946:Plants, Medicinal; D011487:Protein Conformation; D011489:Protein Denaturation; D014118:Toxins, Biological / Q000737:chemistry
D010940:Plant Proteins; D014118:Toxins, Biological; C048826:phaseolin protein, Phaseolus vulgaris