Thomas Haylett

The amino-terminal sequence of silk fibroin peptide CP - a reinvestigation.

Abstract A new amino-acid sequence is proposed for silk fibroin peptide Cp, after automatic Edman degradation studies. The proposed sequence is: Gly-Ala-Gly-Ala-Gly-Ser-Gly-Ala-Ala-Gly-(Ser-Gly-(Ala-Gly) n ) 8 Tyr, where n is usually 2.

Modeccin - A plant toxin inhibiting protein synthesis

Abstract Modeccin is shown to strongly inhibit the ability of HeLa cells to form colonies in vitro . In modeccin treated cells the rate of incorporation of labelled leucine was reduced earlier than that of uridine and thymidine, and the toxin also inhibited protein synthesis in a cell-free system from rabbit reticulocytes. When modeccin was added to human erythrocytes agglutination was induced upon subsequent addition of anti-modeccin indicating that the toxin binds to cell surfaces. This effect was strongly increased after neuraminidase treatment of the cells. Furthermore, neuraminidase treatment of HeLa cells strongly increased their sensitivity to modeccin. The data indicate that modeccin acts by binding to cell surfaces and then somehow interferes with protein synthesis.

Studies on the High-Sulfur Proteins of Reduced Merino Wool: Part III: The Amino-Acid Sequence of Protein SCMKB-IIIB2

The first complete amino-acid sequence of a wool protein is presented. The high-sulfur protein SCMKB-IIIB2, with a molecular weight of 11,260, consists of 97 residues and has an acetylated amino terminal. A notable feature of the protein is that it has a high- and a low-sulfur region. The sequence was determined by examination of the peptides released by various proteolytic enzymes and separated by chromatography on DEAE-cellulose with volatile buffers.

Differences in properties of peanut seed lectin and purified galactose- and mannose-binding lectins from nodules of peanut.

Two lectins were purified by affinity chromatography from mature peanut (Arachis hypogaea L.) nodules, and compared with the previously characterised seed lectin of this plant. One of the nodule lectins was similar to the seed lectin in its molecular weight and amino-acid composition and ability to bind derivatives of galactose. However, unlike the seed lectin, this nodule lectin appeared to be a glycoprotein and the two lectins were only partially identical in their reaction with antibodies prepared against the seed lectin. The other nodule lectin also appeared to be a glycoprotein but bound mannose/glucose-like sugar derivatives, and differed from the seed lectin in molecular weight, antigenic properties and amino-acid composition.

The Toxic Lectin Modeccin

Publisher Summary Modeccin is a protein (toxin ) present in the turnip-like root of the modecca flower. The toxin has striking similarities with two other toxic lectins, abrin and ricin. Owing to the similarities of modeccin to abrin and ricin, the emphasis in this chapter is on those occasions where modeccin differs from abrin and ricin, as well as on purification and assay methods that have been improved for quantitation of modessin. Purification procedure involves extraction and dialysis; gel filtration on Sephadex G-100; DEAC-cellulose chromatography; and affinity chromatography on desialylated fetuin. Assay method discussed includes toxicity test in mice; toxicity to intact cells; sensitization of cells to modeccin by neuraminidase treatment; resistant cells; quantitative measurement of ribosome inactivation; test of indirect hemagglutination; binding of 125I-labeled modeccin to cells.

A Physicochemical Study of the High-Sulfur Proteins from Oxidized Wool

High-sulfur proteins (γ-keratose) have been preferentially extracted from performic acid-oxidized wool with pyridine-acetate buffer (pH = 6.0). It has been shown that the γ-keratose is heterogeneous both on a charge and a molecular size basis by free electrophoresis, chromatography on DEAE-cellulose and calcium phosphate, and gel filtration on Sephadex. Four sub-fractions of γ-keratose which gave single peaks on electrophoresis and ultracentrifugation have been isolated by column electrophoresis. Thorough characterization has shown that these sub-fractions have very different physical properties and amino-acid compositions.

Evidence of differences between related galactose-specific lectins from nodules and seeds of peanut

Abstract The related galactose-binding lectins (GL) from seeds and nodules of peanut (Arachis hypogaea) were similar in their reaction with sugars and several glycoproteins but nodule GL was considerably more reactive with periodate-treated blood group substance (A + H) and asialo-thyroglobulin than was seed GL. Carbohydrate analysis of nodule GL detected the sugars: mannose, galactose, fucose, xylose and N- acetyl glucosamine, supporting earlier evidence that this lectin is a glycoprotein unlike seed GL which is non-glycosylated. Nodule GL contained a major isolectin that did not correspond to the six isolectins in peanut seed GL. The sequence of the first 20 N-terminal amino acid residues of seed GL agreed with published data but only four of the first ten amino acid residues of the purified major isolectin of nodule GL corresponded to those of seed GL. Nodule and seed GL appear to be products of different genes.

Studies on the High-Sulfur Proteins of Reduced Merino Wool: Part II: The Isolation of a Homogeneous Protein

A reinvestigation of a fraction of the high-sulfur proteins SCMKB was made. The proteins were successively fractionated on an electrophoretic, molecular-size, and chromatographic basis. This work resulted in the isolation of a homogeneous protein SCMKB-IIIB2 which has a molecular weight of 11,260, no free amino-terminal group, and contains S-carboxymethyl cysteine as carboxy-terminal residue.

Gas-phase protein sequencing: gas flow control by positive displacement.

A modification of an automatic gas-phase protein/peptide sequencing apparatus is described; this eliminates the effect of the sample on cell gas flow rates. Consistent sequencing chemistry is achieved, yielding data from material that is intractable using standard equipment.