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C Caporale

Publications and source records attributed to C Caporale.

At least 37 records · Page 2Linked to original sources
PubMed1994

Hydrolysis pattern of procasomorphin by gut proteases from plant parasite Heliothis zea, determined by sequence analyses performed on the unfractionated digestion mixtures.

The digestion pattern of procasomorphin, a putative precursor of beta-casomorphins (beta-casein-derived opioid peptides), by gut proteases from the plant parasite insect Heliothis zea has been determined to evaluate the possibility of introducing in plants the gene encoding for this peptide in order to confer resistance to damage by the insect. The method we used is based on the possibility of deducing the sequence of the fragments produced by proteases at different times of digestion by means of automatic Edman degradation performed on the fragment mixtures without any purification steps. This approach can be considered of general utility in studying the digestion of peptides by a mixture of proteases.

Amino Acid Sequence↗
PubMed1993

The amino acid sequence of a protein from wheat kernel closely related to proteins involved in the mechanisms of plant defence.

The amino acid sequence of wheatwin1, a monomeric protein of 125 residues isolated from wheat kernel (variety S. Pastore), is reported. Wheatwin1 is highly homologous (95%) to barwin, a protein from barley seed, which was shown to be related to the C-terminal domain of two proteins encoded by the wound-induced genes win1 and win2 in potato and to a protein encoded by the same domain of the hevein gene (hev1) in rubber tree. Similarly to barwin, wheatwin1 contains six cysteine residues all linked in disulfide bridges and the N-terminal residue is pyroglutamate. Moreover, structural studies performed on wheatwin1 and win1 protein by predictive methods demonstrated that these proteins and barwin are closely related in the secondary structure also. The high level of homology found with the product of win1, win2, and hev1 genes strongly suggests that barwin and wheatwin1 play a common role in the mechanism of plant defence.

Amino Acid Sequence↗
PubMed1991

Assignment of the five disulfide bridges in an alpha-amylase inhibitor from wheat kernel by fast-atom-bombardment mass spectrometry and Edman degradation.

The assignment of the five disulfide bridges in an alpha-amylase monomeric inhibitor from wheat kernel (coded 0.28) was achieved by combining fast-atom-bombardment mass spectrometry (FAB-MS) and automatic sequencing based on Edman degradation. Direct FAB-MS analysis of the native and reduced enzymatic digests of the protein allowed the assignment of three disulfide bridges out of five, including those involving two adjacent cysteine residues. The remaining two disulfide bridges were assigned by sequencing automatically the peptide clusters purified from the tryptic digest of the native protein.

Amino Acid Sequence↗
PubMed1991

Determination of the primary structure of an alpha-amylase inhibitor from wheat kernel by Edman degradation and fast atom bombardment mass spectrometry.

The primary structure of an alpha-amylase inhibitor (coded 0.39) from wheat kernel was determined by fast atom bombardment mass spectrometry and Edman degradation. The sequence is similar to an extent of 97% compared to the other major component of the monomeric isoinhibitor family coded 0.28. The differences consist of the substitution of a single residue and the deletion of two residues in inhibitor 0.39. Neither heterogeneity nor polymorphism were observed in the primary structures of the inhibitors.

Amino Acid Sequence↗
PubMed1990

PROLANG: an expandable software in protein chemistry.

PROLANG is an improved version of the PROSOFT program. Improvements to the old commands were made and new ones were added, PROLANG is an open software that users with BASIC programming experience can easily expand.

Chemical Phenomena↗
PubMed1989

Purification and characterization of a calf thymus protein active on lipid metabolism.

1. This work concerns the purification of a calf thymus protein that increases the binding of human 125I-labeled low density lipoprotein (LDL) on both human skin fibroblasts and a special line of rat liver cells, BRL 3A. 2. It was found that the thymus gland affects cholesterol metabolism via an activation of the LDL receptor pathway. 3. Moreover, the thymus protein active on the LDL receptor pathway has a different amino acid composition and molecular weight from other well-characterized thymic peptides.

Amino Acids↗
PubMed1989

Activity and regulation of calcium-, phospholipid-dependent protein kinase in differentiating chick myogenic cells.

The activity of calcium-, phospholipid-dependent protein kinase (PKc) was measured in (a) total extracts, (b) crude membrane, and (c) cytosolic fractions of chick embryo myogenic cells differentiating in culture. Total PKc activity slowly declines during the course of terminal myogenesis in contrast to the activity of cAMP-dependent protein kinase, which was also measured in the same cells. Myogenic cells at day 1 of culture possess high particulate and low soluble PKc activity. A dramatic decline of particulate PKc activity occurs during myogenic cell differentiation and is accompanied, through day 4, by a striking rise of the soluble activity. The difference in the subcellular distribution of PKc between replicating myoblasts and myotubes is confirmed by phosphorylation studies conducted in intact cells. These studies demonstrate that four polypeptides whose phosphorylation is stimulated by the tumor promoter 12-O-tetradecanoyl phorbol 13-acetate in myotubes, are spontaneously phosphorylated in control myoblasts. Phosphoinositide turnover under basal conditions in [3H]inositol-labeled cells is faster in myoblasts than in myotubes, a finding that may in part explain the different distribution of PKc observed during the course of myogenic differentiation.

Animals↗
PubMed1987

Acetylcholine may regulate its own nicotinic receptor-channel through the C-kinase system.

Acetylcholine (ACh)-activated channel properties were examined on an aneural culture of chick embryo myotubes by using patch-clamp techniques. Changes in conductance, open time and closed time were induced by the selective activator of the calcium- and phospholipid-dependent C-kinase (PKc), 12-O-tetradecanoylphorbol-13-acetate (TPA). The action of TPA was mimicked by exogenous phospholipase C and was blocked by the PKc inhibitor, 1-(5-isoquinolinylsulphonyl)-2-methyl-piperazine. In addition to its gating action, ACh was shown to stimulate phosphoinositide turnover and to translocate PKc from the cytosol to the cell membrane. Both these ACh-induced effects were inhibited by curare and not substantially affected by atropine. Bath-applied ACh outside the patch-pipette in the cell-attached patch-clamp mode, had a strong effect on the ACh-activated channels in the patch membrane, in a way that resembled the action of TPA. These findings raise the possibility that ACh regulates its own nicotinic receptors through the C-kinase system.

Acetylcholine↗
PubMed1986

Altered distribution of protein kinase C in dystrophic muscle cells and its modulation by liposome-delivered phospholipids.

The activity and subcellular distribution of the calcium-phospholipid dependent protein kinase (protein kinase C) were studied in normal and dystrophic muscle cells in vitro. Clonal strains of satellite cells, isolated from normal and dystrophic (C57BL/6J/dydy) mice, differentiate in vitro at a comparable level (over 80% of fusion). Differentiated myotubes were homogenized and separated into a soluble and a particulate fraction. The activity of protein kinase C was assayed in both fractions, and was found to be mainly in the cytosol of normal cells, whereas it was mainly associated to the membrane fraction of dystrophic cells. This altered distribution of the enzyme was likely consequent to alterations in the phospholipid composition of the dystrophic cell membrane, since it was possible to partially revert the situation by modifying the membranes with liposome-delivered phospholipids. Splenic lymphocytes from dystrophic mice showed an altered distribution of protein kinase C similar to that observed in muscle cells. The possible biochemical basis and the functional consequences of this altered distribution of the enzyme in the dystrophic cells are discussed.

Animals↗
PubMed1986

Proliferating and quiescent cells exhibit different subcellular distribution of protein kinase C activity.

The activity of calcium, phospholipid-dependent protein kinase (PKc), which is thought to play an important role in cell proliferation, has been measured in the particulate and soluble fractions of cultured cells, under different proliferative conditions. Our results indicate that proliferating cells display higher PKc activity than quiescent cells. Furthermore, in both normal and transformed cells, PKc is preferentially associated with the particulate fraction when the cells are proliferating, while in mitotically quiescent cells the majority of the enzyme activity is found in the soluble fraction. These data suggest tha PKc activity and subcellular distribution undergo spontaneous changes according to the proliferative state of the cells.

Animals↗
PubMed1986

Calcium-, phospholipid-dependent protein kinase activity of cultured rat Sertoli cells and its modifications by vitamin A.

The activity of the calcium-, phospholipid-dependent protein kinase (PKc) was partially characterized in Sertoli cell cultures prepared from 20-day-old rats. The calcium dependency, the requirements for phosphatidylserine and diolein, as well as the Km for ATP and for the tumor promoter TPA, were determined in total cell extracts. The specific activity of PKc was almost 3-fold higher in the soluble than in the particulate fraction of Sertoli cells. Treatment of cultured Sertoli cells with retinol inhibited, within 1 h of treatment, both the soluble and the particulate fraction-associated PKc activity, with an IC50 of 0.1 microM. Partial inhibition of PKc activity was obtained treating Sertoli cell cultures with FSH, while testosterone was ineffective. However, both FSH and testosterone potentiated the inhibitory effect of retinol. Less differentiated Sertoli cells, obtained from 8-day-old rats, displayed higher PKc activity and a pattern of subcellular distribution of the enzyme opposite to that of Sertoli cells obtained from 20-day-old rats. These data suggest that the actual PKc activity of rat Sertoli cells be negatively regulated by retinol and, spontaneously, during the progression of Sertoli cell differentiation.

Animals↗
PubMed1985

Isolation and characterization of two particle-bound oligoaminopeptidases from human meconium that are different from oligoaminopeptidase of adult small intestine.

Two oligoaminopeptidases (substrate L-leucyl-beta-naphthylamide) have been separated by ion exchange chromatography after Triton solubilization of meconial particles. The quantitatively major form (oligoaminopeptidase II) has been purified to apparent homogeneity. The two meconial oligoaminopeptidases differ from each other in their polyacrylamide gel electrophoretic mobility and isoelectric points. Both meconial enzymes differ from the adult enzyme by having more acidic isoelectric points and different affinities to Helix pomatia lectin-Sepharose columns. Oligoaminopeptidase II has a faster anodal electrophoretic mobility than the adult enzyme but a similar apparent molecular weight and subunit structure. Extensive neuraminidase digestion of meconial oligoaminopeptidase II does not modify the gel electrophoretic mobility of the enzyme. The charge difference between adult and meconial human brush border oligoaminopeptidases is therefore probably due, at least in part, to differences in the carbohydrate composition of these glycoproteins, and differences in the number of terminal or exposed sialic acid residues do not explain the observed charge differences.

Adult↗
PubMed1984

Does casomorphin have a functional role?

Degradation of buffalo beta-casein by various physiological enzymes was studied. Digestion with gastric and pancreatic proteases plus leucine aminopeptidase did not release casomorphins but a putative precursor (procasomorphin) which was further digested by brush border peptidases into peptides differing from casomorphins.

Amino Acids↗
PubMed1984

Fetal forms of oligoaminopeptidase, dipeptidylaminopeptidase IV, and sucrase in human intestine and meconium.

Particles of meconium sedimenting at 105,000 g contain sucrase and various brush border peptidase activities. Oligoaminopeptidase, dipeptidylaminopeptidase, and sucrase solubilized by papain from meconium particles of preterm newborns or from brush border of human fetuses during the 4th month of gestation were compared with the same enzymes prepared from adult jejunal and ileal brush border. The following are characteristics of fetal intestinal brush border enzymes: (a) a faster anodal electrophoretic mobility in polyacrylamide and in agar gel; (b) the same specific activity, as measured by quantitative crossed immunoelectrophoresis utilizing an antiserum against adult brush border membranes; (c) complete fusion of the immunoprecipitation lines with the adult enzymes by using the same antiserum; and (d) a different binding pattern to Helix pomatia lectin and lentil lectin. The results suggest that the charge difference between adult and fetal human brush border enzymes, which causes the difference in the gel electrophoretic mobility, is most probably due, at least in part, to differences in carbohydrate composition of these glycoproteins. Extensive neuraminidase digestion causes no or only minor changes of the electrophoretic mobility of the meconial enzymes. The difference between adult and meconial enzymes is therefore apparently not, or not only, due to different sialic acid content. These results suggest that many intestinal brush border enzymes in fetal life and at birth are in forms structurally different from those in adult life.

Adult↗
PubMed1982

Glycopeptide alterations induced by 12-O-tetradecanoyl phorbol-13-acetate in chick embryo cultured myotubes.

The tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA) specifically inhibits the expression of differentiative traits in cultured chick embryo myotubes, without inducing them to reenter the cell cycle. We evaluated the effect of TPA on glycoconjugate synthesis in cultured myotubes under various experimental conditions. Radioactively labelled glycoconjugates were obtained by labelling control and TPA treated cultured myotubes with radioactive monosaccharides. After chloroform-methanol extraction and extensive pronase digestion, the glycoconjugates were separated on the basis of size on Sephadex G 50 columns. A relative enrichment in larger glycopeptides was induced by TPA treatment of myotubes for 24 or 48 h. Glycopeptide groups were further analyzed by affinity chromatography on ConA Sepharose columns. A marked and reproducible decrease in the affinity of medium size glycopeptides for ConA was observed as a result of TPA treatment of cultured myotubes. These modifications are reversible upon removal of the tumor promoter from the culture medium of pretreated myotubes. The reported effects of TPA, closely resembling those occurring in transformed cells, appear to be due to structural modifications of glycopeptides whose mechanism and role in transformation and modulation of differentiation are discussed.

Animals↗