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PubMed2004

Comparative studies on trifluoroethanol (TFE) state of a thermophilic alpha-amylase and its mesophilic counterpart: limited proteolysis, conformational analysis, aggregation and reactivation of the enzymes.

Detailed circular dichroism (CD), scattering and quenching studies, 1-anilinonaphthalene-8-sulfonate (ANS) binding, irreversible thermoinactivation, activity measurements and proteolytic digestion of bacterial alpha-amylases have been carried out to elucidate the effect of trifluoroethanol (TFE) on the structure of these enzymes. Under high concentrations of TFE both of the alpha-amylases, a thermostable alpha-amylase from Bacillus licheniformis (BLA) and its mesophilic counterpart from Bacillus amyloliquefaciens (BAA), acquire partially folded state characterized by an enhanced content of the secondary structure (helix) and reduced tertiary structures. According to ANS binding studies, we suggest that the TFE states induced by TFE/water mixture are not the molten globule state in the alpha-amylase folding pathway. In addition, data shows significant reversible aggregation of both enzymes in TFE/water mixtures with concentration between 10 and 60% (v/v). However, reversibility is more in case of BAA. As expected, in the absence of TFE, the thermophilic enzyme compared to mesophilic enzyme, shows a greater resistance to digestion by thermolysin. With respect to fluorescence quenching by acrylamide and potassium iodide, the thermophilic enzyme, BLA, is characterized by higher structural flexibility as compared to the BAA. On the other hand, in the presence of TFE, the enzymes are digested by protease to produce large protein fragments. It is proposed that highly helical secondary structures, acquired by BAA and BLA when dissolved in aqueous TFE, prevent binding and adaptation of the protein substrate at the active site of the protease.

Anilino Naphthalenesulfonates↗
PubMed2005

Skin prick test reactivity to supplemental enzymes in cystic fibrosis and pancreatic insufficiency.

BACKGROUND: Patients with cystic fibrosis and pancreatic insufficiency take supplemental pancreatic enzymes of porcine or plant origin on a daily basis. OBJECTIVE: The frequency of immediate skin prick hypersensitivity reactions to such enzymes and the correlations to gastrointestinal symptoms and nutritional status were assessed in a single center prospective descriptive study. METHODS: Skin prick tests using five different freshly prepared porcine pancreatic enzyme preparations, one enzyme preparation of fungal origin, porcine meat and cat epithelia were performed in patients with cystic fibrosis and pancreatic insufficiency and in healthy control subjects. RESULTS: Positive skin tests in the 48 patients with cystic fibrosis were no more frequent than in 21 control subjects. No correlations with the frequency of gastrointestinal symptoms, nutritional status and lung function were found. CONCLUSION: Although immediate hypersensitivity reactions to pancreatic enzyme preparations in subjects with cystic fibrosis are not common, individuals with possible allergic reactions to supplemental enzymes should be identified by skin prick tests and in unclear cases by double-blind placebo-controlled provocation tests.

Adolescent↗
PubMed2004

MAP2 prevents protein aggregation and facilitates reactivation of unfolded enzymes.

It is well established that in addition to its functional role in cell motility, cell division and intracellular transport, cytoskeletal protein tubulin also possesses significant chaperone-like activity. In vitro studies from our laboratory showed that dimeric tubulin can prevent stress induced aggregation of substrate proteins, can resist thermal deactivation of enzymes and can also refold enzymes from their fully denatured state [Manna, T., Sarkar, T., Poddar, A., Roychowdhury, M., Das, K.P. & Bhattacharyya, B. (2001) J. Biol. Chem.276, 39742-39747]. Negative charges of the C-termini of both subunits of tubulin are essential for this chaperone-like property as the deletion of only beta-C-terminus or the binding of a 14-residue basic peptide P2 to the alpha-C-terminus completely abolishes this property [Sarkar, T., Manna, T., Bhattacharyya, S., Mahapatra, P., Poddar, A., Roy, S., Pena, J., Solana, R., Tarazona, R. & Bhattacharyya, B. (2001) Proteins Struct. Funct. Genet.44, 262-269]. Based on these results, one would expect that the microtubular proteins (MTP, tubulin with microtubular-associated proteins, i.e. MAPs bound to the C-terminus) should not possess any chaperone-like activity. To our surprise we noticed excellent chaperone-like activity of MTP. MTP prevents chemical and thermal aggregation of other proteins and can enhance the extent of refolding of fully unfolded substrate enzymes. Because MTP contains tubulin as well as several MAPs bound to the C-termini of tubulin, we fractionated and purified microtubular associated protein 2 (MAP2) and tau using phosphocellulose chromatography. Experiments with purified proteins demonstrated that it is the MAP2 of MTP that exhibits significant chaperone-like activity. This has been shown by the prevention of dithiothreitol-induced aggregation of insulin, thermal aggregation of alcohol dehydrogenase and regain of enzymatic activity during refolding of unfolded substrates. Tau, which shares a homologous C-terminal domain with MAP2, possesses no such activity.

Alcohol Dehydrogenase↗
PubMed1998

Bovine herpesvirus type 1 glycoprotein C expression in MDBK cells and its reactivity in enzyme-linked immunosorbent assay.

Glycoprotein C (gC) of bovine herpesvirus type 1 (BHV-1) is a major viral glycoprotein expressed at high level on the surface of infected cells and on the virion envelope. This glycoprotein is also a major target of immune response at both humoral and cellular levels. The plasmid pRSV-gC having complete coding gene for BHV-1 gC was transfected into MDBK cells and the expression of gC in these cells was detected by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) and immunoblot analysis. Transcription of the gC gene was confirmed by reverse transcription-polymerase chain reaction (RT-PCR) of total RNA isolated from transfected cells. MDBK cells expressing BHV-1 gC were used as antigen in enzyme-linked immunosorbent assay (ELISA) of antibodies against BHV-1 in field sera. The results were found comparable (92.44%) with those obtained with BHV-1 purified antigen.

Animals↗
PubMed1975

The mechanism of aminoacylation of transfer ribonucleic acid. Reactivity of enzyme-bound isoleucyl adenylate.

Isoleucyl adenylate bound to isoleucine:tRNA ligase of Escherichia coli (EC 6.1.1.5; isoleucyl-tRNA synthetase) transfers the isoleucine moiety to tRNA-Ile-E. coli with a half-time of about 35 s at 0 degrees and pH 7.6 in the presence of spermine or Mg2+. If a limited amount of tRNA-Ile is supplied to a mixture of free enzyme and enzyme-bound [14c]isoleucyl adenylate in a medium containing spermine, ATP, and [3H]isoleucine, almost none of the resultant isoleucyl tRNA is derived from preformed enzyme-bound [14C]isoleucyl adenylate. Almost all of the isoleucyl tRNA formed results directly from reaction of free enzyme, ATP, and isoleucine with tRNA. Similar but less clearcut results are obtained when Mg2+ is substituted for spermine. We conclude that isoleucyl adenylate bound to isoleucine:tRNA ligase is not a significant intermediate in the synthesis of isoleucyl tRNA under these conditions.

Adenosine Monophosphate↗