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M K Wood

Publications and source records attributed to M K Wood.

18 recordsLinked to original sources
PubMed1985

Unexpected similarities in the crystal structures of the Mcg light-chain dimer and its hybrid with the Weir protein.

The covalently linked hybrid of two human lambda-type light chains (Mcg and Weir) crystallizes as trigonal bipyramids in ammonium sulfate [Ely et al., Molec. Immun. 22, 85-92 (1985)]. While markedly different in appearance from the barrel-shaped crystals of the parental Mcg dimer, the bipyramids of the hybrid have the same space group: trigonal P3(1)21. Moreover, the unit cell dimensions are practically identical: a = 72.3 A in both proteins; c = 188.1 A in the hybrid and 185.9 A in the Mcg dimer. These observations imply that the crystal packing and the main features of the three-dimensional structures are closely similar in the Mcg X Weir hybrid and the Mcg dimer. The "constant" domains of the Mcg and Weir proteins belong to the same genetic subclass and were expected to interact in comparable ways in hybrids and parental dimers. However, the overall similarities in the "variable" domain pairs in the hybrid and Mcg dimer were completely unpredicted, since the amino acid sequences of the heterologous variable domains differ by 36 residues. By difference Fourier analysis the Weir light chain has been tentatively identified as monomer 1 (heavy-chain analogue) and the Mcg protein as monomer 2 (light-chain analogue) in the hybrid dimer. Substitutions in key positions in the hypervariable loops explain the differences in binding activity of the Mcg and Weir dimers. In the Mcg dimer bis(dinitrophenyl)lysine spans two relatively spacious subsites (A and B), with primary contacts involving tyrosines 34 and 38 of monomer 2. The Weir dimer, which does not bind dinitrophenyl ligands, has serine and phenylalanine in homologous positions. Moreover, the bilateral replacement of valine 48 and serine 91 in Mcg by leucine and methionine in the Weir dimer should effectively block access to subsite B. In the hybrid binding activity for bis(dinitrophenyl)lysine is restored because the Mcg light chain is present as the monomer 2 subunit.

Amino Acid Sequence↗
PubMed1979

A rare cause of ischemic colitis: polyarteritis nodosa.

This paper details the first case report of a patient with fulminant, gangrenous, ischemic colitis caused by polyarteritis nodosa which was successfully treated surgically. Ischemic colitis is a rare complication of polyarteritis nodosa. It should be suspected in patients with a past history of polyarteritis nodosa who develop abdominal pain and rectal bleeding. The identification of cutaneous lesions preoperatively and or mesenteric or serosal vascular beading at operation are helpful in establishing this diagnosis. Prognosis is generally determined by the extent of systemic involvement by polyarteritis nodosa, and death is generally associated with renal failure.

Aged↗
PubMed1971

Structure of concanavalin A at 4.25-ångström resolution.

An electron density map produced by x-ray diffraction analysis of concanavalin A has been calculated to 4.25 A from data of three isomorphous heavy atom derivatives. The crystals are orthorhombic, with unit-cell dimensions of 63.1, 87.0, and 89.2 A for a, b, and c, respectively. The space group is I222, with eight asymmetric units per unit cell. The crystal asymmetric unit contains 27,000 daltons of protein and reflects the chemically unique component (protomer) within the oligomer. Separate chemical studies indicate that the protomer consists of two different polypeptide chains. Four protomers cluster around the intersection of three mutually perpendicular two-fold rotation axes to form a molecule of 108,000 daltons. The molecule can also be subdivided into two-protomer units of 54,000 daltons. Within the two-protomer unit, there are significantly more contacts joining the protomers than there are between adjacent two-protomer units that form the total molecule. These results provide a possible explanation for disagreement in molecular weights obtained in previous ultracentrifugal studies.

Chemical Phenomena↗