Cation dependency of the hydrolytic activity of activated bovine Protein C
The hydrolytic activity of activated bovine plasma Protein C (APC) is dependent upon monovalent or divalent cations. The kinetics of APC activity were examined with a variety of monovalent and divalent cations, and significant differences were observed. Similar studies were performed with des(1-41, light chain)APC (GDAPC), from which all ..gamma..-carboxyglutamic acid residues have been removed. These studies provided useful information concerning the cation dependency. Divalent cations apparently stimulate APC and GDAPC kinetic activity through association at a single ..gamma..-carboxyglutamic acid-independent high affinity binding site. A Mn(II) binding site of this nature of GDAPC was determined by EPR spectroscopy, to possess a dissociation constant of 53 +/- 8 uM. Monovalent cations stimulate GDAPC activity through association at an apparently single binding site that is distinct from the divalent cation site. The monovalent cation , Tl(I), was determined, by /sup 205/Tl(I) NMR spectroscopy, to bind to APC and GDAPC with dissociation constants of 16 +/- 8 mM and 32+/- 11 mM, respectively. Both NMR and EPR spectroscopy have been utilized to estimate topographical relationships between divalent cation sites, monovalent cation sites, and the active site of GDAPC. By observing the paramagnetic effects of either Mn(II) or an active site directed spin-label on the longitudinal relaxation rates of Tl(I) nuclei bound to this enzyme, the average interatomic distance between Mn(II) and Tl(I) was calculated to be 8.3 +/- 0.3 A, and the average distance between Tl(I) and the spin-label free electron was estimated to be 3.8 +/- 0.2 A.
- Research Organization:
- Notre Dame Univ., IN (USA)
- OSTI ID:
- 6790023
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CATIONS
CONFIGURATION INTERACTION
ENZYMES
ELECTRON SPIN RESONANCE
NUCLEAR MAGNETIC RESONANCE
BIOCHEMICAL REACTION KINETICS
BLOOD PLASMA
CATTLE
GLUTAMIC ACID
HYDROLYSIS
MANGANESE COMPOUNDS
THALLIUM 205
AMINO ACIDS
ANIMALS
BIOLOGICAL MATERIALS
BLOOD
BODY FLUIDS
CARBOXYLIC ACIDS
CHARGED PARTICLES
CHEMICAL REACTIONS
DECOMPOSITION
DOMESTIC ANIMALS
HEAVY NUCLEI
IONS
ISOTOPES
KINETICS
LYSIS
MAGNETIC RESONANCE
MAMMALS
MATERIALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
REACTION KINETICS
RESONANCE
RUMINANTS
SOLVOLYSIS
STABLE ISOTOPES
THALLIUM ISOTOPES
TRANSITION ELEMENT COMPOUNDS
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics