Search PubMed⌕ Search

Biomedical subjects

H Hilz

Publications and source records attributed to H Hilz.

At least 73 records · Page 4Linked to original sources
PubMed1980

Antiserum against the catalytic subunit of adenosine 3':5'-cyclic monophosphate-dependent protein kinase. Reactivity towards various protein kinases.

An antiserum against the catalytic subunit C of cyclic AMP-dependent protein kinase, isolated from bovine heart type II protein kinase, was produced in rabbits. Reaction of the catalytic subunit with antiserum and separation of the immunoglobulin G fraction by Protein A-Sepharose quantitatively removed the enzyme from solutions. Comparative immunotitration of protein kinases showed that the amount of antiserum required to eliminate 50% of the enzymic activity was identical for pure catalytic subunit, and for holoenzymes type I and type II. The reactivity of the holoenzymes with the antiserum was identical in the absence or the presence of dissociating concentrations of cyclic AMP. Most of the holoenzyme (type II) remains intact when bound to the antibodies as shown by quantification of the regulatory subunit in the supernatant of the immunoprecipitate. Titration with the antibodies also revealed the presence of a cyclic AMP-independent histone kinase in bovine heart protein kinase I preparations obtained by DEAE-cellulose chromatography. Cyclic AMP-dependent protein kinase purified from the particulate fraction of bovine heart reacted with the antiserum to the same degree as the soluble enzyme, whereas two cyclic AMP-independent kinases separated from the particle fraction neither reacted with the antiserum nor influenced the reaction of the antibodies with the cyclic AMP-dependent protein kinase. Immunotitration of the protein kinase catalytic subunit C from rat liver revealed that the antibodies had rather similar reactivities towards the rat liver and the bovine heart enzyme. This points to a relatively high degree of homology of the catalytic subunit in mammalian tissues and species. Broad applicability of the antiserum to problems related to cyclic AMP-dependent protein kinases is thus indicated.

Animals↗
PubMed1980

Protein-bound mono(ADP-ribose) residues in differentiating cells of Dictyostelium discoideum.

Changes in protein-bound mono(ADP-ribose) residues during development of Dictyostelium discoideum were determined. NAD(H) levels and the amounts of the NH2OH resistant and sensitive subfractions of mono(ADPR) were found not to be different between exponentially growing and aggregation-competent cells in which mitosis had ceased. Divergent changes occurred at the differentiation stages following aggregation as indicated by an increase in the ratio of these subfractions from approx. 1 during the growth plase and aggregation competent stage to 2 in the grex, a stage which follows cell aggregation. The fraction of NH2OH sensitive conjugates closely followed the changes in total cellular protein, while the NH2OH resistant ADPR protein conjugates, when based on protein, increased during the stages following aggregation. NAD(H) and NADP(H) levels per unit DNA decreased significantly during this period. The mono(ADPR) to DNA ratio in D. discoideum is comparable to that in proliferating Physarum polycephalum and to non-proliferating adult rat liver. The total amount of mono(ADPR) residues per nucleus is, however, approximately 70-fold higher in the liver, indicating that the quantity of mono(ADPR) residues is more closely related to the size of the eukaryotic genome than to cell proliferation.

Adenosine Diphosphate Ribose↗
PubMed1980

Negative adaptation to physical training in senile mice.

Three age groups (6, 22 and 27 months) of CWI mice (female, outbred strain) were subjected to a physical training program for up to 5 weeks. During the training period the body weight remained constant in all groups. Hind leg muscle mass increased in response to the exercise in 6 and 22 month old mice but decreased in the senescent (27 months) animals. Physical exercise also increased the key enzyme creatine kinase in the 6 months group and to a lesser degree in the 22 months group. By contrast, senile animals showed a progressive loss of the enzyme throughout the training period. Similar changes - though less-pronounced - were seen with regard to soluble protein and to total DNA. The data indicate that old animals (22 months) are still able to adapt adequately to physical training while senile mice (27 months) respond paradoxically by a negative adaptation to a physical challenge.

Adaptation, Physiological↗
PubMed1980

ADP-ribosylation of nuclear proteins in normal lymphocytes and in low-grade malignant non-Hodgkin lymphoma cells.

Normal lymphocytes and lymphocytes from patients with low-grade malignant non-Hodgkin lymphoma were isolated from blood by a Percoll gradient procedure. Absence of cell proliferation in both cell types was indicated by very low [3H]thymidine incorporation rates. Determination of endogenous protein-bound single ADP-ribose residues by a radioimmunoassay revealed that the leukemic cells had 2.5-times lower levels of the NH2OH-sensitive and a 4-fold lower amount of NH2OH-resistant ADP-ribose . protein conjugate subfractions, respectively, than normal lymphocytes. By contrast, "total" ADP-ribose transferase activity, as measured in homogenates or permeabilized cells in the presence of DNase, was two-times higher in leukemic cells, whereas activity determined in permeabilized cells in the absence of added DNase was practically identical in both cell types. The apparent discrepancy between ADP-ribose transferase activity and endogenous levels of protein-bound single ADP-ribose residues may be explained in part by an enzyme inhibitor present in normal human lymphocytes. NAD + NADH levels were decreased 2.5-fold in the leukemic cells. This decrease, however, does not explain the reduced levels of mono(ADP-ribose) . protein conjugates since the ratio of protein-bound single ADP-ribose residues to NAD is distinctly different in leukemic lymphocytes compared to normal lymphocytes.

ADP Ribose Transferases↗
PubMed1980

Increase of mono(ADP-ribose) protein conjugate levels in rat liver induced by nicotinamide administration.

Protein-bound mono(ADP-ribose) residues were quantitated in the livers of nicotinamide-treated and control rats. Nicotinamide administration led to a rise in NAD+ (2.5-fold) and in protein-bound mono (ADP-ribose) residues (1.5-fold). This increase was higher in the NH2OH-sensitive mono(ADP-ribose) protein conjugates than in the NH2OH-resistant subfraction. NADH, NADP and NADPH levels did not change significantly under these conditions. The findings show that nicotinamide induced an increased ADP ribosylation of new acceptor sites, and not merely an elongation of pre-existing (ADP-ribose)n chains. A correlation of the NAD+ concentration and the extent of post-synthetic modification of nuclear proteins by mono(ADP-ribose) residues was not restricted to nicotinamide-induced changes. It was also seen in various tissues with widely differing NAD+ levels.

Adenosine Diphosphate Ribose↗
PubMed1979

Determination by radioimmunoassay of the sum of oxidized and reduced forms of NAD and NADP in picomole quantities from the same acid extract.

The sum of the amounts of NAD + NADH was determined from the same acid tissue extract with the aid of a highly specific radioimmunoassay for 5'-AMP. NAD was converted to 5'-AMP via ADP-ribose by alkaline treatment while NADH was converted first to ADP-ribose by incubation of the acid extract at 25 degrees C followed by alkaline conversion to 5'-AMP. Removal of phosphate groups in NADP and NADPH by treatment of the extracts with alkaline phosphatase extended the procedure to the quantification of NADP(H). When combined with enzymic analyses of the oxidized coenzyme forms, NAD/NADH and NADP/NADPH ratios could also be obtained from the same extracts. The sensitivity of the test allows quantification of pyridine nucleotides in the range of 0.1--10 pmol.

Adenosine Monophosphate↗
PubMed1979

Aldolase activity and cross-reacting material in lymphocytes of aged individuals.

Aldolase activity was determined in human lymphocytes from 21 donors aged 18-84 years. The lymphocyte extracts contained exclusively aldolase A isozyme. No significnat difference in enzyme activity between adult (18-41 years) and old (56-84 years) age groups was observed. There was also no significant decrease with age of 'cross-reacting material' as determined with monospecific anti-aldolase A antibodies.

Adolescent↗
PubMed1979

[Protein-bound mono (adenosine-diphosphate-ribose) levels during the cell cycle of the slime mold Physarum polycephalum].

In Physarum polycephalum two fractions of ADPR-protein conjugates could be differentiated on the basis of their susceptibility towards hydroxylamine. Quantitation during the cell cycle revealed independent synthesis of the two species, the NH2OH-resistant fraction being formed during S phase, while the NH2OH-sensitive conjugate increased sharply at the S/G2 boundary. These findings indicated that nuclear ADP-ribosylation reactions are more than one function.

Adenosine Diphosphate Sugars↗
PubMed1979

Intrinsic ADP-ribose transferase activity versus levels of mono(adp-ribose)protein conjugates in proliferating Ehrlich ascites tumor cells.

Transition of proliferating Ehrlich ascites tumor cells (3 days after transplantation) to the non-proliferating status (8--14 days after transplantation) was associated with an increase in total mono (ADP-ribose) protein conjugates. This increase was largely confined to the NH2OH-resistant subfraction. When the amounts of mono-(ADP-ribose) conjugates from 20% trichloroacetic acid precipitates were compared with those from 5% perchloric acid precipitates, no significant differences were seen. This fact excludes histone H1 as a major mono (ADP-ribose) acceptor in vivo in these cells. Transition to the resting state was also associated with a small decrease in NAD levels, and with no significant changes of total ADP-ribose transferase activity. However intrinsic ADP-ribose transferase activity as expressed in permeabilized cells was increased, being correlated with the changes in the level of the NH2OH-resistant mono (ADP-ribose) protein conjugates. This shows that alterations in intrinsic transferase activity may, in general, indicate similar alterations in major subfractions of ADP-ribose conjugates. Intrinsic ADP-ribose transferase activity exhibited an inverse relationship to ornithine decarboxylase activity.

Adenosine Diphosphate Ribose↗
PubMed1978

ADP-ribosylated histone H1 from HeLa cultures. Fundamental differences to (ADP-ribose)n-histone H1 conjugates formed into vitro.

ADP-ribosylated histone H1 was isolated from intact HeLa cells grown for 24 h with[3H]-adenosine and compared with ADP-ribosylated histone H1 synthesized from [3H]NAD by isolated HeLa nuclei. Most (ADP-ribose)n-histone H1 conjugates formed in vivo carried single ADP-ribose units, less than one fourth of the total ADP-ribose residues being in the form of oligomeric or polymeric chains. (ADP-ribose)n linked to H1 in vivo was not released by neutral NH2OH to a significant extent. Alkali treatment (pH 10.5) liberated most but not all of the ADP-ribose residues which may indicate the existence of a new type of linkage so far found only in conjugates isolated from intact tissue. No ADP-ribosylated histone H1 complex of higher molecular weight ('H1 dimer') could be detected in intact cells. By contrast, isolated HeLa nuclei formed ADP-ribosylated histone H1 which contained predominantly polymeric ADP-ribose residues. The (ADP-ribose)n residues were linked by NH2OH-sensitive and by NH2OH-resistant, alkali (pH 10.5) labile bonds, the majority of the conjugates appearing in the form of the higher-molecular-weight complex. A comparison with the ADP-ribosylated non-histone proteins indicated that histone H1 formed in vivo carried less than 2.5% of the total protein-bound ADP-ribose residues and less than 1% of the protein-bound ADP-ribose synthesized in vitro.

Cell Nucleus↗