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Biomedical subjects

J I Harris

Publications and source records attributed to J I Harris.

At least 55 records · Page 3Linked to original sources
PubMed1972

Amino Acid Sequence Around the Catalytic Site in Glyceraldehyde-3-Phosphate Dehydrogenase from Bacillus stearothermophilus.

The tryptic peptide containing the active-site cysteine in glyceraldehyde-3-phosphate dehydrogenase from Bacillus stearothermophilus 1503 was isolated after inhibition of the enzyme with (14)C-iodoacetate. The amino acid sequence of the 20-residue peptide was determined by 19 successive cycles of dansyl-Edman degradation. The sequence shows considerable homology with its counterparts from mesophilic sources but differs by the addition of Ala-His-His at the N-terminus and by the substitution of phenylalanine for leucine in the prototype sequence.

Journal Article↗
PubMed1970

Iodination of glyceraldehyde 3-phosphate dehydrogenase.

1. A high degree of homology in the positions of tyrosine residues in glyceraldehyde 3-phosphate dehydrogenase from lobster and pig muscle, and from yeast, prompted an examination of the reactivity of tyrosine residues in the enzyme. 2. Iodination of the enzyme from lobster muscle with low concentrations of potassium tri-[(125)I]-iodide led to the identification of tyrosine residues of differing reactivity. Tyrosine-46 appeared to be the most reactive in the native enzyme. 3. When the monocarboxymethylated enzyme was briefly treated with small amounts of iodine, iodination could be confined almost entirely to tyrosine-46 in the lobster enzyme; tyrosine-39 or tyrosine-42, or both, were also beginning to react. 4. These three tyrosine residues were also those that reacted most readily in the carboxymethylated pig and yeast enzymes. 5. The difficulties in attaining specific reaction of the native enzyme are considered. 6. The differences between our results and those of other workers are discussed.

Alkylation↗
PubMed1969

The use of maleic anhydride for the reversible blocking of amino groups in polypeptide chains.

1. Maleic anhydride was shown to react rapidly and specifically with amino groups of proteins and peptides. Complete substitution of chymotrypsinogen was achieved under mild conditions and the extent of reaction could be readily determined from the spectrum of the maleyl-protein. 2. Maleyl-proteins are generally soluble and disaggregated at neutral pH. Trypsin splits the blocked proteins only at arginine residues and there is frequently selectivity in this cleavage, e.g. in yeast alcohol dehydrogenase and pig glyceraldehyde 3-phosphate dehydrogenase. 3. The group is removed by intramolecular catalysis at acid pH. The half-time was 11-12hr. at 37 degrees at pH3.5 in in-maleyl-lysine or in maleyl-chymotrypsinogen. 4. The unblocking reaction can be used as the basis for a ;diagonal'-electrophoretic separation of lysine peptides and N-terminal peptides, as shown by studies with beta-melanocyte-stimulating hormone.

Alcohol Oxidoreductases↗