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E Doi

Publications and source records attributed to E Doi.

34 records · Page 2Linked to original sources
PubMed1980

Subunit structure of pig kidney cathepsin A.

The two forms of pig kidney cathepsin A (A,L and A,S) were found to be composed of three kinds of polypeptides as common structural subunits with molecular weights of 20,000, 25,000, and 55,000. [32P]-DFP was incorporated into the subunit with a molecular weight of 25,000. This subunit seems to be a catalytic one, on which active serine is present. A subunit composition ratio of 1 : 1 : 1 in native cathepsin A,S was estimated by its molecular weight and those of the subunits. Native cathepsin, A,L also seems to have a subunit composition ratio of 1 : 1 : 1. These results suggest a monomer-polymer relationship between both enzymes.

Animals↗
PubMed1977

Substrate specificities of cathepsin A,L and A,S from pig kidney.

The substrate specificities of two different molecular sizes of cathepsin A, A,L (large form) and A,S (small form), for synthetic substrates were examined kinetically. Both enzymes showed a similar broad substrate specificity against various acyl dipeptides, amino acid esters, and amino acid amides. Z-Phe-Ala and Ac-Phe-OEt were good substrates. Peptides containing hydrophobic amino acids were hydrolyzed rapidly. The presence of hydrophobic amino acid residues, not only at the C-terminal position but also at the second position and probably the third position from the C-terminal, resulted in an increase in the rate of hydrolysis. Peptides containing glycine and proline were hydrolyzed slowly. Inhibition studies with Z-D-Phe-D-Ala and Z-Phe suggested that the peptidase and esterase activities of the enzymes are both catalyzed by the same site of the enzyme molecule, but it remains to be elucidated whether or not the binding sites for peptides and esters are the same.

Alanine↗
PubMed1975

Purification and some properties of cathepsin A of small molecular size from pig kidney.

Cathepsin A [EC 3.4.2.-] of small molecular size (cathepsin A, S) has been purified about 800-fold from pig kidney by procedures including chromatographies on DEAE-Sephadex, SP-Sephadex, and Sephadex G-150. 1. The homogeneity of the purified enzyme was proved by ultracentrifugation and polyacrylamide gel electrophoresis. The molecular weight (100,000) and isoelectric point (pI=5.0) were estimated. 2. The enzyme was remarkably stabilized by sucrose and KCl, and was most stable at pH 5-5.5 in the presence of both stabilizers. The enzyme had not only peptidase activity but also esterase and amidase activity; it was optimally active at pH 5.2 for peptide hydrolysis and at pH 8 for the hydrolysis of esters and amides. 3. Diisopropyl fluorophosphate and iodoacetamide completely inhibited these three activities. 4. The enzyme hydrolyzed various benzoyl- and benzyloxycarbonyl-dipeptides with neutral, acidic, and basic amino acids, and proline in the C-terminal position. The carboxypeptidase nature of the enzyme was proved by its action on an oligopeptide. 5. Several enzymatic properties of cathepsin A, S were almost the same as thoas of cathepsin A of large molecular size (cathepsin A, L) and the crude homogenate.

Animals↗
PubMed1975

Substrate specificity of carboxypeptidase from Watermelon.

The substrate specificity of carboxypeptidase (F-II) purified from watermelon for various synthetic peptides and esters was examined kinetically. The enzyme showed a broad substrate specificity against various carbobenzoxy- and benzyl-dipeptides. Peptides containing glycine or proline were hydrolyzed slowly by the enzyme. Peptides containing hydrophobic amino acids were hydrolyzed rapidly. The presence of hydrophobic amino acid residues, not only at the C-terminal position but also at the second position and probably the third position from the C-terminal resulted in an increase in the rate of hydrolysis. Inhibition studies with diisopropyl flurophosphate and diastereomers of carbobenzoxy-Phe-Ala demonstrated that the peptidase and esterase activities of the enzyme are both catalyzed by the same site of the enzyme molecule, but the binding sites for peptides and esters seem not to be the same. The enzyme also had amidase activity, which was optimal at pH 7.0.

Amidohydrolases↗
PubMedDate not supplied

Radiological findings of vanishing tumor of the stomach.

Four lesions in three patients with so-called vanishing tumor of the stomach are described. Two patients had one lesion each and the third patient two lesions. The lesions were localized in the gastric cardia, angle, and antrum. Radiological findings of these tumors showed a round tumor with smooth surface and regular margins. The edges of the tumors were gently sloping, while the mucosa surrounding the tumor was edematous. The time interval until these tumors disappeared was five days, 20 months, 12 months and seven months, respectively. When the soft appearance of a gastric tumor is suspected in UGI examination, the patient should be re-examined after a month or more, to avoid unnecessary surgery.

Adult↗