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D L Enfield

Publications and source records attributed to D L Enfield.

8 recordsLinked to original sources
PubMed1979

Crayfish carboxypeptidase. Affinity chromatography, characterization and amino-terminal sequence.

In an effort to trace the evolutionary history of the pancreatic metalloexopeptidases, carboxypeptidase has been isolated from the cardia of the crayfish Astacus fluviatilis. The isolation procedure included affinity chromatography on a column of potato carboxypeptidase inhibitor covalently linked to Sepharose. Approximately 25 mg of pure enzyme can be obtained by the present procedure from 50 ml of cardia fluid. The pure enzyme resembles bovine carboxypeptidase B in specificity and is inhibited both by 3-phenyllactate and by 6-aminohexanoate. The pH optimum of activity is about pH 6.5, and the isoelectric point,pH 4.0. Inhibition by typical metal chelating agents (i.e. ethylenediamine tetraacetate and 1,10-phenanthroline) and neutron activation analysis indicate that, like the mammalian enzyme, crayfish carboxypepetidase is a zinc metalloenzyme. The purified enzyme migrates as a single band in cellulose acetate, disc gel and sodium dodecylsulfate gel electrophoresis. The amino acid composition is similar to that of pancreatic carboxypeptidases except for a higher content of acidic amino acid residues. The amino acid sequence of the first 19 amino-terminal residues reveals significant homology to that of pancreatic carboxypeptidases A and B.

Amino Acid Sequence↗
PubMed1979

Comparison of amino acid sequence of bovine coagulation Factor IX (Christmas Factor) with that of other vitamin K-dependent plasma proteins.

The amino acid sequence of bovine blood coagulation Factor IX (Christmas Factor) is presented and compared with the sequences of other vitamin K-dependent plasma proteins and pancreatic trypsinogen. The 416-residue sequence of Factor IX was determined largely by automated Edman degradation of two large segments, containing 181 and 235 residues, isolated after activating Factor IX with a protease from Russell's viper venom. Subfragments of the two segments were produced by enzymatic digestion and by chemical cleavage of methionyl, tryptophyl, and asparaginyl-glycyl bonds. Comparison of the amino acid sequences of Factor IX, Factor X, and Protein C demonstrates that they are homologous throughout. Their homology with prothrombin, however, is restricted to the amino-terminal region, which is rich in gamma-carboxyglutamic acid, and the carboxyl-terminal region, which represents the catalytic domain of these proteins and corresponds to that of pancreatic serine proteases.

Amino Acid Sequence↗
PubMed1975

Bovine factor X1 (Stuart factor). Primary structure of the light chain.

The amino-acid sequence of the light chain of bovine factor X1 is presented. The sequence of 112 of the 140 residues was determined automatically on fragments produced by specific cleavage of arginyl, glutamyl, tryptophanyl, and asparaginyl-glycine bonds. The remainder was determined by conventional procedures. The amino-terminal sequence of the light chain is homologous with the amino-terminal region of bovine prothrombin and, like the latter, appears to contain several residues of a recently discovered unusual amino acid, lambda-carboxy-glutamic acid. The role of this amino acid in the calcium-binding ability of factor X and prothrombin is discussed.

Amino Acid Sequence↗
PubMed1975

Amino-acid sequence of parvalbumin from rabbit skeletal muscle.

Determination of the complete amino-acid sequence of rabbit skeletal muscle parvalbumin is described. The sequence of 86 of the 109 total residues was determined automatically by sequenator analyses of peptides obtained after cleavage with CNBr or with trypsin. The positions of the remaining 23 residues were determined by subtractive Edman degradation of tryptic and chymotryptic peptides. The protein has an acetylated amino terminus. Comparison of the rabbit parvalbumin with those from carp, hake, and pike and with the calcium binding subunit of rabbit muscle troponin indicates that these proteins are homologous. Among the parvalbumins a high degree of identity is observed, especially of residues involved in the binding of calcium or in the formation of the hydrophobic core.

Amino Acid Sequence↗
PubMed1975

Bovine factor X1 (Stuart factor): amino-acid sequence of heavey chain.

The amino-acid sequence of the heavy chain of bovine blood coagulation factor X1 (Stuart factor) isolated before and after activation has been determined. Sequence analysis was performed on fragments obtained by cleavage with cyanogen bromide and by tryptic digestion. Comparison of the complete sequence with those of other hepatic and pancreatic serine proteases demonstrates homology of the heavy chain of activated factor X1 (factor X1a) with the B chain of bovine thrombin as well as with bovine trypsin, chymotrypsins A and B, and porcine elastase. The activation peptide cleaved near the amino terminus by a protease from Russell's viper venom differs in both size and sequence from those of other serine proteases. With three exceptions, all of the residues which are important in the catalytic functions of trypsin and chymotrypsin occur in corresponding loci in the heavy chain of factor Xa. These finding suggest that the three-dimensional structure of the heavy chain is similar to that of the pancreatic serine proteases and that these enzymes have evolved from a common ancestral gene.

Amino Acid Sequence↗