Robert W. Mason

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Cathepsin L was purified to apparent homogeneity from human liver obtained post mortem. It was necessary to treat the homogenate at pH 4.2 and 37 degrees C to release active enzyme. The purification procedure involved ion-exchange chromatography on carboxymethyl-Sephadex and the Mono S column of a Pharmacia fast-protein-liquid-chromatography system. The(More)
The structural basis for the biological specificity of human cystatin C has been investigated. Cystatin C and other inhibitors belonging to family 2 of the cystatin superfamily interact reversibly with target peptidases, seemingly by independent affinity contributions from a wedge-shaped binding region built from two loop-forming inhibitor segments and a(More)
Direct differentiation of embryonic stem (ES) cells into functional motor neurons represents a promising resource to study disease mechanisms, to screen new drug compounds, and to develop new therapies for motor neuron diseases such as spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS). Many current protocols use a combination of retinoic(More)
The complete cDNA nucleotide sequence of a novel cathepsin derived from mouse placenta, termed cathepsin P, was determined. mRNA for cathepsin P was expressed in placenta and at lower levels in visceral yolk sac, but could not be detected in a range of adult tissues. The expression pattern of this protease indicates that it probably plays an important role(More)
The major excreted protein (MEP) purified from Kirsten-virus-transformed 3T3 fibroblasts and mature human cathepsin L were compared in respect to a number of catalytic criteria and found to be similar. The Mr of MEP is 39,000, whereas that of mature human cathepsin L is 30,000. Sequence data suggested that MEP could be a pro-form of mouse cathepsin L. Both(More)
Posttranslational histone modifications and histone variants form a unique epigenetic landscape on mammalian chromosomes where the principal epigenetic heterochromatin markers, trimethylated histone H3(K9) and the histone H2A.Z, are inversely localized in relation to each other. Trimethylated H3(K9) marks pericentromeric constitutive heterochromatin and the(More)
Leucocyte elastase in catalytic amounts was observed to rapidly cleave the Val-10-Gly-11 bond of the human cysteine-proteinase inhibitor cystatin C at neutral pH. The resulting modified inhibitor had size and amino acid composition consistent with a cystatin C molecule devoid of the N-terminal Ser-1-Val-10 decapeptide. Leucocyte-elastase-modified cystatin C(More)
A series of peptidyldiazomethanes was synthesized and tested as inactivators of the cysteine proteinases calpain II, cathepsin L and cathepsin B. Inactivators that react rapidly and that show a degree of selectivity between the enzymes were identified. Z-Tyr(I)-Ala-CHN2 (where Z represents benzyloxycarbonyl) reacts rapidly with cathepsin L and more slowly(More)
The mammalian embryo is encased in a glycoproteinaceous coat, the zona pellucida (ZP) during preimplantation development. Prior to implantation, the blastocyst must undergo 'hatching' or ZP escape. In hamsters, there is a thinning of the ZP followed by a focal lysis and a complete dissolution of the ZP during blastocyst hatching. Earlier studies from our(More)
We used site-directed mutagenesis to alter the specificity of human cystatin C, an inhibitor with a broad reactivity against cysteine proteinases. Nine cystatin C variants containing amino acid substitutions in the N-terminal (L9W, V10W, V10F and V10R) and/or the C-terminal (W106G) enzyme-binding regions were designed and produced in Escherichia coli. It(More)