PubMed Health⌕ Search

Biomedical subjects

W A Hendrickson

Publications and source records attributed to W A Hendrickson.

At least 127 records · Page 7Linked to original sources
PubMed1977

Pseudosymmetry in the structure of myohemerythrin.

The three-dimensional structure of the protein myohemerythrin from retractor muscles of the sipunculan worn Themiste zostericola has been explored for the existance of approximately symmetry operators that locally interrelate portions of the molecule. First, the electron denisty distribution at 5.5 A resolution was examined. A local 2-fold axis that transposes the C-D helix pair into the A-B helix pair was found and refined by the method of least squares. The match in electron densities for a pure 2-fold rotation had a correlation coefficient of 0.56. Next, a comprehensive search was made for rotational symmetry in the Patterson function of an isolated molecule. The rotation function based on data to 6 A spacings showed a major peak, 72% of the self-peak height, that confirmed the result from electron density correlations. In addition, a pattern of lower level peaks revealed approximate point group symmetry as high as D4. Finally, the amino acid sequence has been inspected for evidence of a repeated structure. The level of amino acid identities between positions in the A-B and C-D helix pairs is 28%. Several factors are discussed to suggest that this homology, although low, is nonetheless significant.

Amino Acid Sequence↗
PubMed1975

Tertiary structure of myohemerythrin at low resolution.

X-ray diffraction studies have produced a low resolution image and also located the iron atoms of a monomeric hemerythrin from muscles of a sipunculan worm. These results reveal the course of the polypeptide chain and some details of the active center.

Hemerythrin↗
PubMedDate not supplied

Structure of trimeric haemerythrin.

Several simplifying structural principles have been developed from the considerable data contained in the three-dimensional structures of proteins determined in the past two decades. One of these is based on the observation that particular folding motifs often occur in a variety of structural and functional settings. The compact bundle of four antiparallel alpha-helices, first seen in the structure of myohaemerythrin, is an example. Several non-haemerythrin proteins have since been found to have the same folding pattern, and haemerythrins themselves exist in a wide variety of quaternary arrangements. The unusual ability of the haemerythrin fold to associate as dimers, trimers, tetramers, octamers or higher aggregates provides an opportunity for examining structural diversity in subunit association. We have used X-ray crystallography to study the subunit structure of trimeric haemerythrin from a Siphonosoma species. We report here that the pattern of intersubunit helix-helix interactions differs from the most common mode of association of other helix-bundle proteins. In a novel approach to structure analysis at low resolution, experimental phases for the structure determination were based on anomalous scattering from the iron atoms native to haemerythrin, using the new resolved-anomalous phasing procedure.

Animals↗
PubMedDate not supplied

The reactivity of anti-peptide antibodies is a function of the atomic mobility of sites in a protein.

To study the nature of antigenic recognition, antibodies have been prepared against a set of peptide sequences representing both highly mobile and well-ordered regions of myohaemerythrin, based on X-ray crystallographic temperature factors. Anti-peptide antibodies against highly mobile regions react strongly with the native protein; anti-peptide antibodies from well-ordered regions do not. Mobility is a major factor in the recognition of the native protein by anti-peptide antibodies; this may be of general significance in protein-protein interactions.

Animals↗