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B Wiederanders

Publications and source records attributed to B Wiederanders.

At least 73 records · Page 4Linked to original sources
PubMed1985

Distribution of cathepsin D immunoreactivity in the central nervous system of rat and selected brain regions of man.

The regional distribution and cellular localization of cathepsin D immunoreactivity was demonstrated at the light microscopic level in the CNS of rat and man by use of unlabelled immunoenzyme technique. A wide but uneven distribution was substantiated for the rat brain. Furthermore, we present evidence that antiserum produced against rat liver enzyme is capable of recognizing cathepsin D in human brain.

Animals↗
PubMed1985

[Proteolytic degradation of glucagon by human erythrocytes].

Human erythrocytes possess a proteolytic activity degrading glucagon (and insulin) even at very low concentrations with a high degree of efficiency. The enzyme which likely belongs to the class of insulin-glucagon-proteinases, can be inhibited by chelating agents, such as ethylenediamine tetraacetic acid and o-phenanthroline, thiol blocking reagents, such as p-chloromercuribenzoate and N-ethylmaleimide as well as by proteinase inhibitors directed against serine proteinases, such as Contrykal and Trasylol. No inhibition could be shown by leupeptin. Insulin in an equimolar range is capable of inhibiting glucagon degradation competitively. Dithioerythritol stimulates the degrading activity. Co++, Zn++, Mn++ and Ca++ prevent the o-phenanthroline mediated inhibition of glucagon degrading activity, whereas Mg++, Cu++, Cd++ and Fe+++ have an inhibitory effect. The glucagon degradation exhibits a pH optimum at 7,1 with an apparent Km of 4.4 X 10(-6) mol/l. The insulin-glucagon-proteinase in human erythrocytes is supposed to have a regulatory influence within the carbohydrate pathway.

Cations, Divalent↗
PubMed1984

Accumulation of inactive cathepsin D in old rats.

From the 2nd to the 29th month of life seven different rat organs (liver, heart, kidney, lung, spleen, skeletal muscle, intestinal mucosa) show a continuous increase in the concentration of protein reacting with rabbit antiserum against rat liver cathepsin D. However, the activity of aspartate proteinases, probably mainly cathepsin D, does not show the same increase. This result is interpreted as accumulation of enzymatically inactive but immunologically reactive cathepsin D. This phenomenon, which is well known for some cytosolic enzymes in senescent animals, is first reported to occur for a lysosomal proteinase as well.

Aging↗
PubMed1984

The insulin and glucagon degrading proteinase of rat liver. Separation of the proteinase from the thiol-proteindisulfide oxidoreductases.

Insulin degrading enzymes of rat liver cytosol, the so-called insulin and glucagon degrading proteinase (IGP, EC 3.4.23.5), and two forms of the insulin degrading thiol-protein-disulfide oxidoreductase/isomerase (glutathione-insulin transhydrogenase, TPO, EC 1.8.4.2/5.3.4.1) were separated from each other and partially purified on DEAE-Sephadex. The highly purified proteinase was obtained by polyacrylamide gel electrophoresis of the DEAE-Sephadex-purified enzyme fraction and was used to produce monospecific antibodies to the IGP in rabbits. Strong evidence is given that the insulin and glucagon degrading proteinase is an autonomous enzyme existing in addition to the TPO forms in the cytosol of the liver. Combined action of the proteinase and the TPO system on radioiodinated insulin under various conditions in vitro revealed an independent and non-sequential degradation of insulin by these two enzyme systems.

Animals↗
PubMed1984

The insulin and glucagon degrading proteinase of rat liver: a metal-dependent enzyme.

Insulin and glucagon degrading proteinase (EC 3.4.23.5) purified from rat liver cytosol was characterized using radioiodinated insulin and glucagon as substrates. Maximum activity for breakdown of both hormones was found at pH 8.1. Thiol blocking reagents as well as indole derivatives inhibit the proteinase, whereas pepstatin, leupeptin, bestatin, elastatinal, antipain, chymostatin and phosphoramidon do not have any effect. Although the Km values and maximal velocities of insulin and glucagon breakdown deviate strongly from each other, the specificity constants (kcat/Km) for both substrates are nearly identical. The insulin and glucagon degrading proteinase, known as a thiol-dependent enzyme, was found to be also a metallo enzyme. Chelating agents, such as EDTA, EGTA, bipyridine and o-phenanthroline show a concentration dependent inhibition. The strongest inhibitor found was o-phenanthroline. Zn++, Co++, Mn++, and to a smaller extent Cd++ and Fe++, are capable of preventing the o-phenanthroline mediated inhibition. Removal of the protein-bound metal(s) results in a nearly total and irreversible loss of enzymatic activity.

Animals↗
PubMed1984

Distribution of thiol-protein disulfide oxidoreductase, insulin-glucagon proteinase and cathepsin D in different cell types of the rat liver.

Cathepsin D (EC 3.4.23.5), the insulin and glucagon degrading proteinase (IGP, EC 3.4.22.-) and the thiol-protein disulfide oxidoreductase (TPO, EC 1.8.4.2, 5.3.4.1) participate in the intracellular protein degradation, the last one also in post-protein-synthetic processing. The distribution of these enzymes was determined in isolated liver parenchymal cells, Kupffer cells and endothelial cells by means of immunochemical methods in order to further characterize these cell types. The cathepsin D content, expressed as microgram enzyme per mg protein, is about 3 fold higher in endothelial cells and about 5 to 24 fold higher in Kupffer cells than in parenchymal cells. This result confirms an earlier report which is based on the activity determination. The TPO concentration is highest in parenchymal cells with half of that concentration in Kupffer cells and one third in endothelial cells. About 0.5% of the total liver protein is represented by this enzyme. The IGP has been found to be totally absent in non-parenchymal cells. It represents, therefore, together with the glucose-6-phosphatase a valuable marker enzyme for parenchymal cells of rat liver.

Animals↗
PubMed1982

The ribosomal serine proteinase, cathepsin R. Occurrence in rat-liver ribosomes in a cryptic form.

Ribosomes have been shown to contain a proteolytic activity, characterized as an endopeptidase with serine in the active center. The enzyme has been given the name cathepsin R, following the recommendations of Barrett et al. (in a publication from the Cold Spring Harbor Laboratory, New York) for naming new proteinases. The present paper contains evidence that cathepsin R in rat liver ribosomes is present in a cryptic form. Upon dissociation of ribosomes to subunits (and to minor extent also by 0.5 M KC1 washes), the cryptic proteinase is released. Activation of the released cathepsin R is effected by equilibration with 2 M NaC1/0.05 M sodium acetate, pH 4.8. The molecular weight of free cathepsin R is 25 000-30 000.

Animals↗
PubMed1982

Inhibition of cysteine proteinase activity by Z-Phe-Phe-diazomethane and of aspartic proteinase activity by pepstatin in different organs from some animals and isolated cells from rat liver.

Two methods have been developed to discriminate simultaneously between the main part of cysteine proteinase activity (cathepsin L) and all aspartic proteinase activity (mainly cathepsin D) in rat organs, using Z-Phe-Phe-CHN2 which at 5 mumol/l completely inhibits cathepsin L from rat liver and, on the other hand, pepstatin which at 0.5 mumol/l completely inhibits cathepsin D. Substrates are double-labeled cytosol proteins from rat liver at pH 3.0 or azocasein in 3 mol/l urea at pH 5.0. Several organs from rat, pigeon, frog and carp have been investigated using these methods. Especially kidneys from rat, frog and carp contain a high Z-Phe-Phe-CHN2 inhibited activity. Investigating the different liver cell types we could confirm earlier findings that Kupffer cells and endothelial cells contain more pepstatin inhibited activity than parenchymal cells.

Animals↗
PubMed1981

The turnover of liver cytosol proteins in very old rats.

The protein degradation rate of total liver homogenate as well as of the liver cytosol was measured according to the method introduced by GARLICK and coworkers (Biochem. J. 156 (1976) 657-663). The half-lives were 2.85 days (cytosol) and 2.45 days (homogenate) in the group consisting of 29 months old rats and 2.35 days and 2.15 days in the control group consisting of 12 months old rats. The amount of cathepsin D determined in some organs by two independent methods (immunological and enzymic) revealed differences in the group of the old animals. We suggest the accumulation of cross reacting material of cathepsin D in rats of the old group. It is perhaps one of the reasons why a slower protein degradation is observed in old animals.

Aging↗
PubMed1981

[Determination of the half-life of liver proteins in very old rats].

The turnover rate of rat liver cytosol proteins was calculated by means of NaH14CO3-pulse labeling and following the decay of this label up to the 10th day after application of the precursor. Maximum incorporation of the precursor into the cytosol proteins has been found to be 40 minutes after its administration. The half-life was calculated in animals 21 and 27 months of age to be 2,8 days, which is by 50% longer in comparison to adult young animals.

Aging↗
PubMed1979

Lysosomal cysteine proteinases.

Cathepsin B has so far been the most investigated cysteine (thiol) proteinase of lysosomes. The use of cytosol proteins as substrates has allowed the detection of two new lysosomal cysteine proteinases from rat liver: the endoaminopeptidase cathepsin H and cathepsin L, which splits almost no synthetic substrates but has a more than 10-fold higher specific activity with proteins as substrates than other mammalian cysteine proteinases. The properties of cathepsin L are compared with those of other cysteine proteinases (cathepsin B,H,N,S and others) from different tissues in relation to substrate specificity and sensitivity to inhibitors. A new test system for determining cathepsin L allows us to investigate the distribution of this enzyme between different cell types and to speculate about the special role of cysteine proteinase in intracellular protein degradation.

Animals↗
PubMed1979

The ribosomal serine proteinase: cathepsin R.

As has been known for several years, thoroughly purified ribosomes contain a firmly bound serine proteinase with an optimum of activity at neutral pH. The present paper shows that the activity is found in free cytoplasmic ribosomes as well as in ribosomes detached from the membranes of the endoplasmic reticulum of rat liver. After ribosome dissociation, the proteinase activity is found only on the 40 S subunits. Recovery of the proteinase in the proteins of whole ribosomes or of 40 S subunits amounts to 44 and 65%, respectively. Ribosomes purified both from plant (Euglena) and bacterial (Acinetobacter) cells contain a serine proteinase having an activity quite comparable to that of rat liver ribosomes. In view of the recommendations of BARRETT et al. ( in REICH, RIFKIN and SHAW (eds).: Proteinases and Biological Control, Cold Spring Harbour Lab., 1975, p. 481), who no longer restrict the name "cathepsin" to acid or even lysosomal proteinases, we propose the name " ccathepsin R" for this ribosomal serine proteinase.

Animals↗
PubMed1978

The age dependence of intracellular proteolysis: changes of the substrate proteins.

Liver cytosol proteins of young (4--6 months) and old (18--27 months) rats were degraded in vitro by papain, pronase, trypsin, pepsin, cathepsin D from rat liver and a soluble lysosomal enzyme mixture from rat liver. We could demonstrate the capability of the latter enzyme mixture to degrade proteolytically the cytosol proteins of young animals about 20% faster than those of the older animal group. Digesting radioactive labelled "young" cytosol in the presence of unlabelled "old" cytosol the possibility could be excluded, that this effect was due to an inhibitor of macromolecular size present in the "old" cytosol.

Aging↗
PubMed1978

[Age dependent structural changes in non collagen proteins and their consequences in protein turnover degradative rate (author's transl)].

During the aging process the occurence of proteins with physico-chemical properties different from their juvenile counterparts are observed in many organisms. The probable molecular mechanisms of such variations are reviewed. Although no direct evidence could be found in the literature for an altered breakdown rate of such a single "old" protein, the possible influence of this kind of modifications in protein molecules on their over all degradative rate is discussed.

Aging↗
PubMed1977

Cathepsin L. A new proteinase from rat-liver lysosomes.

1. Cathepsin L was purified from rat liver lysosomes by cell fractionation, osmotic disruption of the lysosomes in the lysosomal mitochondrial pellet, gel filtration of the lysosomal extract and chromatography on CM-Sephadex. 2. Cathepsin L is a thiol proteinase and exists in several multiple forms visible on the disc electropherogram. By polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate its molecular weight was found to be 23000-24000. The isoelectric points of the multiple forms of cathepsin L extended from pH 5.8-6.1 ascertained by analytical isoelectric focusing. 3. Using various protein substrates, cathepsin L was found to be the most active endopeptidase from rat liver lysosomes acting at pH 6-7. In contrast to cathepsin B1, its capability of hydrolyzing N-substituted derivatives of arginine is low and it does not split esters. 4. Greatest activity is obtained close to pH 5.0 with 70-90% of maximal activity at pH 4.0 and pH 6.0 and 30-40% at pH 7.0. 5. The enzyme is strongly inhibited by leupeptin and the chloromethyl ketone of tosyl-lysine. Leupeptin acts as a pseudo-irreversible inhibitor. 6. The enzyme is stable for several months at slightly acid pH values in the presence of thiol compounds in a deep-frozen state.

Animals↗
PubMed1977

Aging changes in intracellular protein breakdown.

Using radioactively labelled cytosol proteins as substrates we were able to exclude the possible accumulation of any specific inhibitor for the lysosomal proteases in rat liver cytosol during the aging process. There were also no gross changes in the molecular weight patterns of these proteins during the aging process. The percentage of more hydrophobic proteins seems to be identical in both the "old" and "young" cytosol proteins. From immunological experiments we suppose a qualitative change in the composition of rat liver cytosol proteins or of their properties during the aging process.

Aging↗