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D Boulter

Publications and source records attributed to D Boulter.

79 records · Page 5Linked to original sources
PubMed1970

The amino acid sequence of Phaseolus aureua L. (mung-bean) cytochrome c.

The amino acid sequence of Phaseolus aureus L. (mung-bean) cytochrome c has been determined. The molecule consists of a single polypeptide chain of 111 amino acid residues and is homologous with other mitochondrial cytochromes c. Comparison with the amino acid sequence of wheat-germ cytochrome c (Stevens, Glazer & Smith, 1967) shows 14 differences. On alignment with mammalian cytochromes c, mung-bean cytochrome c has an N-acetylated ;tail' of eight amino acid residues similar to that found in wheat-germ cytochrome c. Of the 22 positions in wheat-germ cytochrome c that contain amino acid residues unique to these positions, 20 were found to contain the same ones in mung-bean cytochrome c. The in-N-trimethyl-lysine residues reported for wheat-germ cytochrome c (Delange, Glazer & Smith, 1969) in positions 72 and 86 were also found in these positions in mung-bean cytochrome c. The sequence was determined from 3mumol, by using chymotryptic and tryptic peptides which were analysed by the ;dansyl'-Edman method (Gray & Hartley, 1963a), with confirmation by amino acid analysis.

Amino Acid Sequence↗
PubMed1970

The amino acid sequence of Helianthus annuus L. (sunflower) cyrochrome c deduced from chymotryptic peptides.

Peptides derived from digestion of 1 mumol of sunflower cytochrome c with chymotrypsin were separated by paper electrophoresis. The sequences of these peptides were determined by using the dansyl-Edman method (Gray & Hartley, 1963) and confirmed by analysis of their amino acid composition. Comparison of the set of peptides with the chymotryptic peptides of mung-bean (Thompson, Laycock, Ramshaw & Boulter, 1970) and wheat germ (Stevens, Glazer & Smith, 1967) cytochrome c shows a clear homology. The complete sequence of sunflower cytochrome c was established by alignment of the sunflower peptides with the sequences of mung bean cytochrome c and wheat germ cytochrome c.

Amino Acid Sequence↗
PubMed1970

Kinetic studies of formate dehydrogenase.

1. The kinetic mechanism of formate dehydrogenase is a sequential pathway. 2. The binding of the substrates proceeds in an obligatory order, NAD(+) binding first, followed by formate. 3. It seems most likely that the interconversion of the central ternary complex is extremely rapid, and that the rate-limiting step is the formation or possible isomerization of the enzyme-coenzyme complexes. 4. The secondary plots of the inhibitions with HCO(3) (-) and NO(3) (-) are non-linear, which suggests that more than one molecule of each species is able to bind to the same enzyme form. 5. The rate of the reverse reaction with carbon dioxide at pH6.0 is 20 times that with bicarbonate at pH8.0, although no product inhibition could be detected with carbon dioxide. The low rate of the reverse reaction precluded any steady-state analysis as the enzyme concentrations needed to obtain a measurable rate are of the same order as the K(m) values for NAD(+) and NADH.

Adenine Nucleotides↗
PubMed1969

The subunit structure of jack-bean urease.

1. Urease of specific activity 160-180 Sumner units/g. (Sumner, 1951) was purified from jack-bean meal. The preparation was pure on the basis of polyacryl-amide-gel electrophoresis and N-terminal studies. 2. By using both the 1-fluoro-2,4-dinitrobenzene method and the phenyl isothiocyanate method a single N-terminal methionine residue was found. 3. A single C-terminal sequence -Tyr-Leu-Phe was found by studies with carboxypeptidase A, carboxypeptidase B and hydrazinolysis. 4. N-Bromosuccinimide cleavage showed that five unique tryptophan sequences were present: Trp-Ala, Trp-Glu, Trp-Gly, Trp-Met and Trp-Arg. 5. Polyacrylamide-gel electrophoresis in sodium dodecyl sulphate showed that urease had a subunit molecular weight of 76000. 6. The yield of N- and C-terminal amino acids, the number of tryptic peptides and tryptophan sequences and the above polyacrylamide-gel electrophoretic measurement all suggest that urease contains a single structural subunit of molecular weight 75000.

Amino Acid Sequence↗