Biomedical subjects

U Ganesan

Publications and source records attributed to U Ganesan.

11 recordsLinked to original sources

PubMed1994

Regulation of the phosphorylation of calpain II and its inhibitor.

Phosphorylation of calpain II (or its inhibitor) by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK), cyclic GMP-dependent protein kinase (G-PK), and protein kinase C (PK-C) was analyzed by SDS-polyacrylamide gel electrophoresis and autoradiography. Among these protein kinases, the catalytic subunit of A-PK exhibited the strongest phosphorylations of both calpain II and its inhibitor. Arachidonic acid and staurosporine effectively inhibited phosphorylation regardless the type of kinase tested. Despite its lack of effect on the phosphorylation of calpain II by the catalytic subunit of A-PK, sphingosine moderately enhanced the phosphorylation of calpain II by G-PK. Other agents, including phosphatidylethanolamine, phosphatidylinositol and 1, 2-dioleoyl-sn-glycerol, had no significant effect.

Binding Sites↗

PubMed1994

Enhanced phosphorylation of yeast endogenous substrates by phosphatidylglycerol (dioleoyl) and phosphatidylinositol.

Protein kinases and their endogenous substrates from the crude cytosolic extract of Saccharomyces cerevisiae were coeluted in the fraction 13 on DE-52 column chromatography. Analyses of SDS-polyacrylamide gel electrophoresis and autoradiography revealed that the peptides between 14 and 34 kDa were the major phosphorylated substrates. In the presence of Ca2+ and Mg2+, the phosphorylation was suppressed strongly by the regulatory subunit of cAMP-dependent protein kinase and slightly by oleic acid, whereas it was augmented appreciably by phosphatidylglycerol (dioleoyl) and phosphatidylinositol.

Adenosine Triphosphate↗

PubMed1993

Modulation of the activity of calpain II by phosphorylation--changes in the proteolysis of cyclic AMP-dependent protein kinase (peak II, DEAE).

The proteolysis of the 32P-labeled holoenzyme of cyclic AMP-dependent protein kinase (A-PKII:DEAE, peak II fraction) was analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. The contaminants of the A-PKII and calpain II apparently did not interfere with the accuracy of this highly sensitive analysis. Phosphorylation of calpain II by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK) greatly enhanced the proteolysis of A-PKII, whereas phosphorylation by protein kinase C (PK-C) or cyclic GMP-dependent protein kinase (G-PK) slightly altered the proteolysis.

Calpain↗

PubMed1993

Regulation of the phosphorylation of histones and glycogen synthase.

The phosphorylation of histones and glycogen synthase by protein kinases was analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. The phosphorylation of histone III-S by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK) or cGMP-dependent protein kinase (G-PK) was inhibited by archidonic acid, sphingosine and staurosporine. Using the catalytic subunit of A-PK, the phosphorylation of histone VIII-S was inhibited by Ca2+, arachidonic acid and staurosporine; the phosphorylation of histone II-S was inhibited by phosphatidyl ethanolamine, phosphatidyl inositol, arachidonic acid and staurosporine; and the phosphorylation of glycogen synthase was inhibited by arachidonic acid and staurosporine. After being phosphorylated by the catalytic subunit of A-PK, calpain II with 4 microM Ca2+ was less effective in degrading histone III-S, which had been prephosphorylated by PK-C.

AMP-Activated Protein Kinases↗

PubMed1992

Regulation of Staphylococcus protease using complement, interferon and immunoglobulin as substrates.

The effects of various agents on the cleavage of serum albumin, interferon, immunoglobulin and complement component C1q by the extracellular protease from Staphylococcus aureus were analysed by SDS-polyacrylamide gel electrophoresis. Arachidonic acid moderately stimulated the proteolysis of serum albumin, interferon and complement component. Phosphatidic acid effectively enhanced the proteolysis of serum albumin and IgG, whereas it inhibited the cleavage of IgM. The proteolysis of IgG was appreciably enhanced by sphingosine. In contrast, phosphatidyl choline and phosphatidyl glycerol were shown to have an inhibitory effect on the proteolysis of IgG and IgM. Phosphatidyl serine, phosphatidyl inositol and phosphatidyl ethanolamine also inhibited the proteolysis of IgG. The failure of any of these agents to exert a persistent effect on the cleavage of all substrates, revealed the complexity of the interactions among the agent, the substrate and the protease.

Complement C1q↗

PubMed1991

Regulation of fungal proteolysis on cyclic AMP-dependent protein kinase, cyclic AMP phosphodiesterase, glycogen synthase and histones.

Limited proteolysis of catalytic and regulatory subunits of cyclic AMP-dependent protein kinase (A-pk), cyclic AMP phosphodiesterase, glycogen synthase, and histones by fungal protease (type XIX) was analyzed by the digested peptide bands in SDS polyacrylamide gel electrophoresis. The modulatory effects on proteolysis by nucleotides, polypeptides, and phospholipids may greatly depend on the intrinsic nature of substrates. The proteolysis of the regulatory subunit of A-pk and glycogen synthase was not regulated by nucleotides and nucleic acids. In comparison, phosphatidyl serine, cardiolipin, and pepstatin A stimulated the proteolysis of the catalytic subunit of A-pk. Whereas, lambda DNA (Hind III digest), t-RNA, GTP-, phosphatidyl serine, sphingosine inhibited the proteolysis of cyclic AMP phosphodiesterase. Moreover, MS2 RNA, lambda DNA, t-RNA, dGTP, Phosphatidyl serine, phosphatidyl inositol, antipain, and chymostatin exerted inhibitory proteolytic effect on histone VIII-S. Some of these agents also had similar inhibitory effect on other types of histones (types III-S and VII-S). The inhibitory effect of phosphatidyl serine on proteolysis of histone may be due to their interaction which was monitored by the drastic increase of uv absorbance.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1991

Proteolysis of interleukin-2, interferon and immunoglobulin by venoms.

Limited proteolysis by venoms was analysed by the cleaved peptide band(s) in SDS-polyacrylamide gel electrophoresis. The venom from Crotalus atrox degraded interferon, interleukin-2, IgG, IgM, and a crude form of acetyl cholinesterase but had no effect on IgA. Although the venom from Androctonus australis did not exert appreciable proteolysis on any of the immunoglobulins it had potent proteolytic activities against interferon and interleukin-2. The venom from Vespula maculifrons had only a minor proteolytic effect on interferon. The proteolysis by venoms was not effectively inhibited by alpha 1-antitrypsin or a2-macroglobulin. Moreover, no appreciable proteolytic activity was detected in the venoms from Bufo arenarum, Apis mellifera and Heloderma suspectrum.

Animals↗

PubMed1990

Stimulation of proteolysis on calmodulin.

The proteolysis of calmodulin by fungal protease (type XIX) was greatly enhanced in the presence of dGTP and MS2 RNA. Whereas, only moderate proteolytic activation on bacterial proteases (type XXVI) was observed in the presence of MS2 RNA. No appreciable proteolysis of calmodulin by bacterial protease (type IX) was observed. Proteolytic fragments of calmodulin cleaved by fungal protease exhibited unusual low mobility during SDS-polyacrylamide gel electrophoresis. Similar decreased electrophoretic mobility was also noted in the proteolytic fragments of other Ca2(+)-binding proteins including S-100A protein and parvalbumin.

Animals↗

PubMed1990

A further study on the regulation of microbial proteases.

Various agents were tested for their effects on microbial proteases, which activity was monitored by the analysis of cleaved peptide bands in SDS-polyacrylamide gel electrophoresis. Using casein as a substrate, fungal protease (type XIX) was inhibited by the phenyl methyl sulphonyl fluoride, chymostatin, antipain and leupeptin, while bacterial protease (type XXVI) was inhibited by phosphatidyl glycerol, phosphatidyl inositol and sphingosine. MS2 RNA exerted minor inhibition on the bacterial proteolysis of regulatory subunits of cyclic AMP-dependent protein kinase (A-PK). The cleavage of DNA binding protein by both proteases was inhibited, in the presence of MS2 RNA and lambda DNA. In comparison, phosphatidyl serine slightly stimulated the fungal protease on the cleavage of ribonuclease T1. RNA polymerase is a good substrate of the bacterial protease as indicated by the generation of multiple cleaved peptide fragments, whereas alkaline phosphatase is not susceptible to proteolysis.

Aspergillus↗

PubMed1990

Inhibitory effect of transfer RNA on protein kinases from baker's yeast and rat skeletal muscle.

Sephadex G-200 gel filtration of DNA cellulose-treated crude extracts of rat skeletal muscle, revealed a broad peak-fraction of tRNA-inhibitory protein kinases (PK) coeluted endogenous substrates. In comparison, the elution profile of baker's yeast exhibited multiple peak-fractions of tRNA-inhibiting PK. Various tRNA all showed inhibition to PK. In the presence of regulatory subunit of cyclic AMP-dependent protein kinase, tRNA did not exert synergetic inhibition on PK. Moreover, the interaction of tRNA with active muscle PK fractions could not be monitored by the increment of absorbance at 340 nm. tRNA had no significant regulatory effect on the phosphorylation of actin and myosin.

Animals↗

PubMed1989

Interaction between cortisol and microbial proteases.

Binding (or interaction) of cortisol with microbial molecule(s) was observed by employing Bio-Gel HTP affinity chromatography and subsequently by fluorescence spectrophotometry. Molecule(s) in the crude extract of baker's yeast and in other microbial proteases exhibited varied degrees of cortisol-binding. Bacterial protease (type IX) had highest, while the type XXVI enzyme had the lowest, binding capacity. In addition, these two proteases exhibited a distinct difference in the alterations of ultraviolet spectra due to interaction with cortisol. Using casein as a substrate, cortisol, CTP, trypsin inhibitor or leupeptin appreciably inhibited type IX protease at low concentrations of Ca2+. However, thyroxine had no effect on this protease.

Bacteria↗