Antithrombin III and its interaction with heparin. Comparison of the human, bovine, and porcine proteins by /sup 1/H NMR spectroscopy
/sup 1/H NMR has been used to characterize and compare the structures of antithrombin III from human, bovine, and porcine plasma as well as to investigate the interactions of each of these proteins with heparin fragments of defined length. The amino acid compositions of the three proteins are very similar, which is reflected in the gross features of their /sup 1/H NMR spectra. Human antithrombin III has five histidine residues, bovine has six, and porcine has five. The C(2) proton from each of these residues gives a narrow resonance and titrates with pH; the pK/sub a/'s are in the range 5.15-7.25. It is concluded that all histidines in each protein are surface residues with considerable independent mobility. The carbohydrate chains in each protein also give sharp resonances consistent with a surface location and motional flexibility. The /sup 1/H spectra are sensitive to heparin binding. Although heparin resonances obscure protein resonances in the region 3.2-6.0 ppm, difference spectra between antithrombin III with and without heparin show clear perturbation of a small number of aromatic and aliphatic protein protons. For human antithrombin III, it was shown that heparin fragments 8, 10, and 16 sugar residues in length result in almost identical perturbations to the protein. In contrast, tetrasaccharide results in fewer perturbations. Significantly, intact high molecular weight heparin causes the same spectral perturbations as the 16-residue fragment. These data are discussed in terms of requirements for heparin binding.
- Research Organization:
- Vanderbilt Univ. School of Medicine, Nashville, TN
- OSTI ID:
- 6219864
- Journal Information:
- Biochemistry; (United States), Vol. 26:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANTICOAGULANTS
NUCLEAR MAGNETIC RESONANCE
AMINO ACID SEQUENCE
CATTLE
ELECTROPHORESIS
HEPARIN
MAN
NMR SPECTRA
PH VALUE
PROTONS
SWINE
AMINES
ANIMALS
BARYONS
CARBOHYDRATES
DOMESTIC ANIMALS
DRUGS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HEMATOLOGIC AGENTS
MAGNETIC RESONANCE
MAMMALS
MOLECULAR STRUCTURE
MUCOPOLYSACCHARIDES
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
POLYSACCHARIDES
PRIMATES
RESONANCE
RUMINANTS
SACCHARIDES
SPECTRA
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics