Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.1.4.3 (
phospholipase C
)
18,461
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
L-Asparaginase of Tetrahymena pyriformis is a lipoprotein with relative M(r) approximately 200 kDa and one subunit size of 39 kDa. This enzyme also exhibits protein kinase activity and it is autophosphorylated in tyrosine residues. Phosphorylation-dephosphorylation of
L-asparaginase
resulted in complete loss or activation by more than 10-fold of its catalytic activity. Both native and dephosphorylated forms of
L-asparaginase
are inactivated by
phospholipase C
and this inactivation can be reversed by the addition of lipids. Based on these results a working hypothesis is suggested that
L-asparaginase
of T. pyriformis exists in four interconvertible forms: Form A, phosphorylated complexed with lipids, form HA, dephosphorylated (highly active), form I, free of lipids, (inactive) and form B, free of lipids and phosphate.
...
PMID:A model for the regulation of the activity of L-asparaginase/ kinase enzyme of Tetrahymena pyriformis. 250 74
A membrane-bound
L-asparaginase
(
EC 3.5.1.1
) of Tetrahymena pyriformis was purified to homogeneity. The purified enzyme is a lipoprotein, since it is inactivated by
phospholipase C
and its activity is restored by the addition of naturally occurring lipids, such as phosphatidylcholine, triolein and oleyl acetate. The relative effectiveness of a variety of phospholipids, free saturated and unsaturated fatty acids, or neutral lipids, such as esters of fatty acids and glycerides, with respect to the activation of purified
L-asparaginase
is compared. Enzyme activity is reconstituted in the presence of lipids and evidence for the formation of an enzyme-phospholipid complex is presented. The data of this report suggest that
L-asparaginase
may have a requirement for lipids that reconstitute a physiological hydrophobic environment, similar to the one existing in vivo.
...
PMID:In vitro alterations of L-asparaginase activity of Tetrahymena pyriformis by lipids. 314 10
In T. thermophila two forms of
L-asparaginase
(
EC 3.5.1.1
) were extracted and purified to near homogeneity which are associated with membranes. These two forms of
L-asparaginase
, I or II, act optimally at pH 8.6 and do not present any glutaminase or kinase activity. Both activities reach maximal values at the stationary phase of growth of T. thermophila. L-Asparaginases are solubilized by treatment of the particulates with 2% w/v Triton X-100 and then by sodium phosphate buffer pH 8.0. Both forms cross reacted with antibodies raised against T. pyriformis
L-asparaginase
and show isoelectric points 7.4 and 8.2. Among the metals tested, Ca2+ is the most effective in activating
L-asparaginase
I or II activity. Sorbitol alone up to 30% w/v in the assay mixture activates more than 10 x fold the activity of
L-asparaginase
II. Incubation of
L-asparaginase
I or II with increasing concentration of
phospholipase C
results in gradually loss of their activities. The relative effectiveness of a variety of phospholipids to reconstitute enzyme activity is presented as well.
...
PMID:Two forms of L-asparaginase in Tetrahymena thermophila. 801 91
This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of various food additives, including flavouring agents, with a view to recommending acceptable daily intakes (ADIs) and to preparing specifications for identity and purity. The first part of the report contains a general discussion of the principles governing the toxicological evaluation and assessment of intake of food additives (in particular, flavouring agents). A summary follows of the Committee's evaluations of technical, toxicological and intake data for certain food additives (
asparaginase
from Aspergillus niger expressed in A. niger, calcium lignosulfonate (40-65), ethyl lauroyl arginate, paprika extract,
phospholipase C
expressed in Pichia pastoris, phytosterols, phytostanols and their esters, polydimethylsiloxane, steviol glycosides and sulfites [assessment of dietary exposure]) and 10 groups of related flavouring agents (aliphatic branched-chain saturated and unsaturated alcohols, aldehydes, acids and related esters; aliphatic linear alpha,beta-unsaturated aldehydes, acids and related alcohols, acetals and esters; aliphatic secondary alcohols, ketones and related esters; alkoxy-substituted allylbenzenes present in foods and essential oils and used as flavouring agents; esters of aliphatic acyclic primary alcohols with aliphatic linear saturated carboxylic acids; furan-substituted aliphatic hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids and related esters, sulfides, disulfides and ethers; miscellaneous nitrogen-containing substances; monocyclic and bicyclic secondary alcohols, ketones and related esters; hydroxy- and alkoxy-substituted benzyl derivatives; and substances structurally related to menthol). Specifications for the following food additives were revised: canthaxanthin; carob bean gum and carob bean gum (clarified); chlorophyllin copper complexes, sodium and potassium salts; Fast Green FCF; guar gum and guar gum (clarified); iron oxides; isomalt; monomagnesium phosphate; Patent Blue V; Sunset Yellow FCF; and trisodium diphosphate. Re-evaluation of flavouring agents for which estimated intake was based on anticipated poundage data was carried out for 2-isopropyl- N,2,3-trimethylbutyramide (No. 1595) and L-monomenthyl glutarate (No. 1414). Annexed to the report are tables summarizing the Committee's recommendations for intakes and toxicological evaluations of the food additives considered.
...
PMID:Evaluation of certain food additives. 2011 97
