scholarly journals Trypanosoma brucei brucei variant surface glycoprotein contains non-N-acetylated glucosamine

1986 ◽  
Vol 234 (2) ◽  
pp. 481-484 ◽  
Author(s):  
A M Strang ◽  
J M Williams ◽  
M A J Ferguson ◽  
A A Holder ◽  
A K Allen

The C-terminal amino acid of the variant surface glycoprotein of the parasitic protozoan Trypanosoma brucei brucei is glycosylated and the oligosaccharide has been shown to contain glucosamine. By acid hydrolysis, HNO2 deamination and 1H-n.m.r. studies we have demonstrated that the amino group of this glucosamine is not N-acetylated and is most probably unmodified.

1983 ◽  
Vol 209 (1) ◽  
pp. 261-262 ◽  
Author(s):  
A A Holder

The C-terminal amino acid of the variant surface glycoprotein from Trypanosoma brucei is glycosylated. For two variant proteins that terminate in an aspartic acid and a serine residue respectively, it was shown that the sugar side chain is linked through ethanolamine to the alpha-carboxy group of the amino acid.


Nature ◽  
1976 ◽  
Vol 263 (5578) ◽  
pp. 613-614 ◽  
Author(s):  
PAMELA J. BRIDGEN ◽  
GEORGE A. M. CROSS ◽  
JOHN BRIDGEN

Author(s):  
Marylène Hublart ◽  
Lucia Mendonça-Previato ◽  
François Boutignon ◽  
Guillemette Huet-Duvillier ◽  
Pierre Degand

1983 ◽  
Vol 209 (2) ◽  
pp. 481-487 ◽  
Author(s):  
G Allen ◽  
L P Gurnett

The locations of the six disulphide bonds and the single free cysteine residue in a variant surface glycoprotein, VSG 117, from the African trypanosome Trypanosoma brucei have been determined to be Cys-14-Cys-140, Cys-121-Cys-182, Cys-389-Cys-404, Cys-398-417, Cys-447-Cys-461 and Cys-455-Cys-468. Cys-244 bears the single thiol group, which is unreactive towards 2-nitro-5-thiocyanobenzoate in the native molecule and is probably buried. Biosynthetically incorporated [35S]cysteine aided the location of the disulphide bonds. Two proteinase-resistant glycosylated domains, each containing two disulphide bonds, were identified in the C-terminal region of the glycoprotein. Details of purification of [35S]cysteine-containing peptides, and Tables of amino acid analyses, are presented in Supplementary Publication SUP 50119 (32 pages), which has been deposited with the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1981) 193,5.


1985 ◽  
Vol 230 (1) ◽  
pp. 195-202 ◽  
Author(s):  
D G Jackson ◽  
M J Owen ◽  
H P Voorheis

A simple new technique was developed for the rapid purification of either the membrane-bound or the released forms of the variant surface glycoprotein of Trypanosoma brucei in high yield. Whole cells were used as the source of the membrane-bound form, and the supernatant of benzyl alcohol-treated cells was used as the source of the released form. The technique was based on extraction of the acid-treated protein into chloroform/methanol, followed by selective re-partition into aqueous salt solution. The yield of purified protein was found to be dependent critically on a low pH during the extraction/re-partition stages. This finding and the ability to cycle the protein repeatedly through organic and aqueous phases in a strictly pH-dependent manner suggested that the protein could undergo fully reversible denaturation/renaturation only while in an extensively protonated form. The yield was independent of the polarity of the organic phase and the protein concentration over a wide range. After purification, both forms retain their ability to react with specific antibody raised against the authentic native protein purified by conventional means. The amino acid composition and the identity of the N-terminal amino acid was the same for both forms of the protein. In addition, both forms had blocked C-terminal residues. There were determined to be 1.13 × 10(7) copies of the variant surface glycoprotein per cell.


1969 ◽  
Vol 112 (5) ◽  
pp. 609-616 ◽  
Author(s):  
W. S. Pierpoint

1. The reactions of amino acids and peptides with the o-quinones produced by the enzymic oxidation of chlorogenic acid and caffeic acid have been studied manometrically and spectrophotometrically. 2. Amino acids, except lysine and cysteine, react primarily through their α-amino groups to give red or brown products. These reactions, which compete with the polymerization of the quinones, are followed by secondary reactions that may absorb oxygen and give products with other colours. 3. The ∈-amino group of lysine reacts with the o-quinones in a similar way. The thiol group of cysteine reacts with the quinones, without absorbing oxygen, giving colourless products. 4. Peptides containing cysteine react with the o-quinones through their thiol group. 5. Other peptides, such as glycyl-leucine and leucylglycine, react primarily through their α-amino group and the overall reaction resembles that of the N-terminal amino acid except that it is quicker. 6. With some peptides, the secondary reactions differ from those that occur between the o-quinones and the N-terminal amino acids. The colours produced from carnosine resemble those produced from histidine rather than those from β-alanine, and the reactions of prolylalanine with o-quinones are more complex than those of proline.


1975 ◽  
Vol 145 (3) ◽  
pp. 459-467 ◽  
Author(s):  
D Parris ◽  
L S Swart

The complete amino acid sequence of mohair protein, SCMKB-M1.2 (97 residues), was determined. The protein was isolated from reduced and carboxymethylated mohair by chromatography on DEAE-cellulose phosphate. Peptides for sequence determination were obtained by digestion with trypsin, pepsin, chymotrypsin, thermolysin and papain, and were fractionated by DEAE-cellulose chromatography, paper chromatography and electrophoresis. The sequence of the peptides were determined by the Edman degradation method (by use of both the Beckman Sequence and a non-automatic procedure), and by partial acid hydrolysis. The protein is closely homologous to wool protein SCMKB-IIIB2, and also contains acetylated alanine as N-terminal amino acid.


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