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Biomedical subjects

K J Machin

Publications and source records attributed to K J Machin.

8 recordsLinked to original sources
PubMed1994

Crystal structure of human chorionic gonadotropin.

The three-dimensional structure of human chorionic gonadotropin shows that each of its two different subunits has a similar topology, with three disulphide bonds forming a cystine knot. This same folding motif is found in some protein growth factors. The heterodimer is stabilized by a segment of the beta-subunit which wraps around the alpha-subunit and is covalently linked like a seat belt by the disulphide Cys 26-Cys 110. This extraordinary feature appears to be essential not only for the association of these heterodimers but also for receptor binding by the glycoprotein hormones.

Amino Acid Sequence↗
PubMed1990

High-performance liquid chromatography of amino acids, peptides and proteins. C. Characterisation of coulombic interactive regions on hen lysozyme by high-performance liquid anion-exchange chromatography and computer graphic analysis.

The molecular characteristics of the dominant anion-exchange binding site of hen egg white lysozyme (HEWL) has been investigated using a combination of high-performance liquid chromatographic techniques and computer graphic analysis of the X-ray crystallographic structure. These studies have indicated that the site of highest electrostatic potential, in terms of the density of negatively charged amino acid side chains, is located around the catalytic cleft area. The four residues tentatively identified to be involved in the electrostatic binding domain were aspartic acid 48, 52, 101 and glutamic acid 35. The number of these charged groups correlated with the maximum value of the chromatographically determined retention parameter (Zc value). Variations in the range of experimental Zc values obtained under different elution conditions have been interpreted in terms of conformational flexibility of the structural domains of HEWL which result in the opening or closure of the catalytic cleft during the retention process.

Amino Acid Sequence↗
PubMed1989

Preliminary X-ray diffraction analysis of human chorionic gonadotropin.

Hexagonal bipyramidal crystals of deglycosylated human chorionic gonadotropin have been grown using the method of vapor diffusion against ammonium sulfate. These crystals grow to nearly 0.4 mm along each axis, diffract to better than 3.5-A resolution and are relatively stable to irradiation. The crystals belong to the hexagonal space group P6(1)22 or enantiomer, and have unit cell parameters a = b = 88.7 A and c = 177.3 A.

Chorionic Gonadotropin↗
PubMed1988

The effect of fast protein liquid chromatography (FPLC) cationic exchange purification on the crystallization of a monoclonal Fab fragment.

Fast protein liquid chromatography cationic exchange purification to homogeneity of a monoclonal Fab fragment has resulted in an improvement in the quality of crystals for X-ray diffraction studies. This improvement is displayed in a well-defined crystal morphology, reproducibility of crystal growth, and increased resolution of diffraction data.

Chromatography, Ion Exchange↗
PubMed1986

Binding of heparin to human platelet factor 4.

Platelet factor 4 is a small protein (Mr 7756) from the alpha-granules of blood platelets which binds strongly to and neutralizes the anticoagulant properties of heparin. From an analysis of X-ray crystallographic data a model for the binding of platelet factor 4 to heparin is proposed.

Binding Sites↗
PubMed1985

Crystallization and preliminary crystallographic data of the Fab fragment of an anti-phenylalanine hydroxylase monoclonal antibody.

Two crystal habits, one rod shaped and the other square prismatic, of the Fab fragment of a monoclonal anti-phenylalanine hydroxylase antibody have been grown using the method of vapour phase diffusion against polyethylene glycol 6000. The square prisms diffract to better than 2.8 A, belong to the space group P1 and have unit cell parameters a = 41.8 A, b = 50.3 A, c = 114.7 A, alpha = 97.6 degrees, beta = 91.7 degrees, gamma = 91.0 degrees, while the rod-shaped crystals belong to the space group P212121, have unit cell parameters a = 105.6 A, b = 119.8 A, c = 82.2 A and diffract to 3.5 A resolution.

Antibodies, Monoclonal↗
PubMed1985

Three-dimensional structure of goose-type lysozyme from the egg white of the Australian black swan, Cygnus atratus.

The egg white of C. atratus contains two forms of lysozyme, a 'chick-type' which is similar to that found in the egg white of the domestic hen, and a 'goose-type' similar to that found in the egg white of the Embden goose. The molecular structure of the goose-type lysozyme has been determined at a resolution of a 2.8 A by X-ray crystallographic analysis. The structure consists of two domains linked by a long stretch of alpha-helix. In all, there are seven helical segments in the structure. While there is no amino acid sequence homology with either hen egg-white or bacteriophage T4 lysozymes, there are portions of the structure where the folding of the main chain is similar to that found in portions of either hen egg-white lysozyme or T4 lysozyme or both. In particular, there is a consistency of structure in the arrangement of acid groups in the catalytic site. G-o plots calculated for this structure and for the bacteriophage T4 lysozyme structure show that both have similar 'modules' of structure with boundaries occurring at structurally equivalent positions. Three of the common boundaries are equivalent structurally to three of the four module boundaries observed in G-o plots of hen egg-white lysozyme. The variation in the position of the remaining boundary may be related to differences in substrate binding.

Animals↗