Characterization of a soluble form of dipeptidyl peptidase IV from pig liver

Soluble dipeptidyl peptidase IV (EC 3.4.14.5) was purified from the 100,000 X g supernatant fraction of pig liver homogenate. The purified enzyme had the same properties as, and immunological identity with, the membrane-bound enzyme which was described previously. However, the purified enzyme had a pattern of molecular heterogeneity different from the membrane-bound enzyme; this was shown by isoelectric focusing. Carbohydrate analysis revealed that the soluble enzyme contained glucose, which is not found in the membrane-bound one, and less fucose, mannose, and sialic acid than the latter. From these results, we conclude that the soluble form of dipeptidyl peptidase IV in pig liver is closely related to the membrane-bound enzyme, but is not simply a proteolytically solubilized product of it.     

Immunochemical identity of dipeptidyl aminopeptidase IV from pig serum,liver, submaxillary gland and kidney

Summary The enzymes which were extracted by autodigestion from the microsomal fractions of the pig kidney, liver and submaxillary gland and from the serum showed an immunochemical identity by a double immunodiffusion test. But the kidney enzyme had a different pI-value from the pI-values of the enzymes of other organs.This investigation was supported by a grant from the Ministry of Education, Japan to K. M. F. We would like to thank Dr Toshiharu Nagatsu (Department of Life Chemistry, Graduate School at Nagatsuta, Tokyo Institute of Technology, Yokohama, Japan) for helpful suggestions, Mr Moritoshi Sato (Matsumoto Meat Inspection Station, Matsumoto, Japan) for their generous supply of pig organs and Ajinomoto Co. Inc., Tokyo, Japan, for the gift of Gly-Pro-p-nitroanilide tosylate. Technical assistance of Miss K. Yanagisawa is gratefully acknowledged.     

Immunochemical identity of dipeptidyl aminopeptidase IV from pig serum, liver, submaxillary gland and kidney.

The enzymes which were extracted by autodigestion from the microsomal fractions of the pig kidney, liver and submaxillary gland and from the serum showed an immunochemical identity by a double immunodiffusion test. But the kidney enzyme had a different pI-value from the pI-values of the enzymes of other organs.     

Increased activity of dipeptidyl peptidase IV in serum of hepatoma-bearing rats coincides with the loss of the enzyme from the hepatoma plasma membrane

The specific activity of dipeptidyl peptidase IV (DPP IV E.C. 3.4.14.-) in the plasma membrane of Morris hepatoma 9121 or hepatoma 7777 was 3.5% and 2.9%, respectively, of that in the plasma membrane of rat liver. The enzyme activity in the serum of hepatoma-bearing rats was 141% (hepatoma 91219) and 162% (hepatoma 7777) of the normal value. Cytochemical investigation showed that the DPP IV activity was almost completely absent from the hepatoma cell plasma membrane and was not sequestered within these cells. Indirect immunofluorescence staining with a polyclonal antibody directed against DPP IV indicated that the loss of activity was due to the absence of DPP IV molecules in the plasma membrane. The possibility that the enzyme is transferred from the membrane into the serum as a result of structural alterations is discussed.     

Increased activity of dipeptidyl peptidase IV in serum of hepatoma-bearing rats coincides with the loss of the enzyme from the hepatoma plasma membrane

Summary The specific activity of dipeptidyl peptidase IV (DPPIV E.C. 3.4.14.-) in the plasma membrane of Morris hepatoma 9121 or hepatoma 7777 was 3.5% and 2.9%, respectively, of that in the plasma membrane of rat liver. The enzyme activity in the serum of hepatoma-bearing rats was 141% (hepatoma 91219) and 162% (hepatoma 7777) of the normal value. cytochemical investigation showed that the DPP IV activity was almost completely absent from the hepatoma cell plasma membrane and was not sequestered within these cells. Indirect immunofluorescence staining with a polyclonal antibody directed against DPP IV indicated that the loss of activity was due to the absence of DPP IV molecules in the plasma membrane. The possibility that the enzyme is transferred from the membrane into the serum as a result of structural alterations is discussed.     

Deficiency of membrane-bound dipeptidyl aminopeptidase IV in a certain rat strain

The activity of membrane-bound dipeptidyl aminopeptidase IV (EC 3.4.14.5) was found to be markedly reduced in the Fischer 344 rat strain compared with that in the Wistar strain. Analysis of membrane proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Ouchterlony immunodiffusion revealed the specific absence of this enzyme molecule in the Fischer 344 strain.     

Deficiency of membrane-bound dipeptidyl aminopeptidase IV in a certain rat strain

Summary The activity of membrane-bound dipeptidyl aminopeptidase IV (EC 3.4.14.5) was found to be markedly reduced in the Fischer 344 rat strain compared with that in the Wistar strain. Analysis of membrane proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Ouchterlony immunodiffusion revealed the specific absence of this enzyme molecule in the Fischer 344 strain.     

Paper electrophoresis of soluble proteins from regenerating rat liver

Riassunto Gli autori hanno studiato il comportamento delle proteine e delle glicoproteine solubili del fegato rigenerante di ratto mediante l'elettroforesi su carta. La colorazione con Amidoschwarz mostra che il comportamento elettroforetico delle proteine di fegato rigenerante è praticamente sovrapponibile a quello del fegato normale. La colorazione secondoKöiw eGrönwall dimostra che le glicoproteine diminuiscono nei primi giorni dopo l'atto operatorio, tornando però alla normalità circa 30 giorni dopo l'epatectomia.

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This investigation was aided by a grant from C.N.R., Rome, and was done during the tenure by one of us (G. G.) of a Scholarship from C.N.R., Rome.     

Immunoelectrophoresis of soluble proteins isolated from cellular fractions of regenerating rat liver

Riassunto Gli autori hanno studiato, mediante elettroforesi su agar ed immunoelettroforesi, il comportamento delle proteine solubili isolate dalle frazioni citoplasmatica e mitocondriale del fegato rigenerante di ratto. Sono state rilevate alcune modificazioni delle proprietà immunochimiche di taluni componenti proteici.     

Studies on the dye-binding fraction of soluble liver proteins from rats fed aminoazo dyes

Résumé Les auteurs ont étudié le profil électrophorétique du surnageant de foies de rats, nourris aux colorants azoïques cancérogènes. La fraction, dite protéine «h», a été isoléc et on a déterminé son poids moléculaire, sa teneur en colorant lié, en vitamines et en acides nucléiques et sa composition en acides aminés.

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This investigation was supported by the Institutional Grant 71 from the American Cancer Society and the Grant C-355 of the National Cancer Institute, Public Health Service to Drs.J. A. Miller andE. C. Miller, to whom we are greatly indebted.     

Agar electrophoresis of soluble proteins isolated from cellular fractions of CCl4-treated rat liver

Riassunto Gli autori hanno studiato, mediante elettroforesi su agar, il comportamento delle proteine solubili isolate dalle diverse frazioni cellulari di epatociti di ratto, in corso di steatosi da CCl₄.A carico delle frazioni nucleare e mitocondriale è stata osservata una diminuzione dei componenti più e meno dispersi, con un raggruppamento in zone a motilità intermedia, pari a quella delle ₁-globuline sieriche o delle albumine, accanto ad una riduzione del numero dei componenti proteici chiaramente individuabili.Analoghe modificazioni sono state rilevate a carico dei componenti glico- e lipoproteici — nella sola frazione mitocondriale.     

Paper electrophoresis of soluble proteins of rat liver mitochondria

Riassunto Mediante elettroforesi su carta si dimostra la presenza nei lisati di mitocondri di fegato di ratto di almeno 5 componenti proteici. Le colorazioni specifiche dimostrano la presenza di 3 frazioni lipoproteiche e di altrettante glicoproteiche. I lisati dei mitocondri vennero ottenuti qer trattamento delle particelle con Triton X-100.     

Guinea pig liver cytosol has an L-threonine deaminase activity distinct from L-serine deaminase]

Using sodium sulfate precipitation, "Sephadex G200" gel filtration and polyacrylamide gel electrophoresis, a L-threonine desaminase was demonstrated in the Guinea-Pig liver cytosol. This enzyme was separated from the guinea pig liver L-serine desaminase possessing an auxiliary activity on L-threonine substrate described by us in a previous work. The optimals for pH (7,1) and temperature (+ 55 degrees C) and the apparent molecular weight (134,000 + 20,000) were established.     

Interaction between the soluble and particulate neuraminidases of chick liver

Summary The sum of the neuraminidase activities found in the isolated soluble and particulate fractions of chick liver was considerably higher than that observed in the cytoplasmic extract from which these fractions were obtained. Addition of increasing amounts of particulate neuraminidase to a constant amount of the soluble preparation resulted in a progressive loss of enzyme activity.This investigation was supported in part by U. S. Public Health Service Grant NS09176 from the National Institutes of Health.