Solvent viscosity effects on the rate of side-chain rotational isomerization in a protein molecule
The activated rotation of the tyrosine 35 ring in bovine pancreatic trypsin inhibitor has been simulated in model solvents that have extremely different viscosities but that are otherwise identical. Both simulations are at 300 K, but one solvent corresponds to liquid water and the other to a hypothetical glassy water. Although the ring is located in the surface region of the protein, the freezing of the solvents reduces the rate constant for rotation by only 50%. The time required to complete individual transitions is somewhat lengthened, apparently due to slowed relaxation both of ring-solvent interactions and of the conformation of the protein matrix that surrounds most of the ring. The slowing of these relaxations also leads to the reduction in the rate constant: the persistence of ring environments that favor rotation increases the likelihood that the ring will return to the transition-state region soon after passing through it, rather than being trapped in a stable state.
- Research Organization:
- Univ. of Houston, TX
- OSTI ID:
- 5954332
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 91:19
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
TYROSINE
ROTATIONAL STATES
WATER
SOLVENT PROPERTIES
AQUEOUS SOLUTIONS
MEDIUM TEMPERATURE
MOLECULAR MODELS
PANCREAS
THEORETICAL DATA
TRYPSIN
VISCOSITY
AMINO ACIDS
BODY
CARBOXYLIC ACIDS
DATA
DIGESTIVE SYSTEM
DISPERSIONS
ENDOCRINE GLANDS
ENERGY LEVELS
ENZYMES
EXCITED STATES
GLANDS
HYDROGEN COMPOUNDS
HYDROLASES
HYDROXY ACIDS
INFORMATION
MATHEMATICAL MODELS
MIXTURES
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PEPTIDE HYDROLASES
SERINE PROTEINASES
SOLUTIONS
400201* - Chemical & Physicochemical Properties
550200 - Biochemistry