Dramatic enhancement of enzymatic activity in organic solvents by lyoprotectants

1993 ◽  
Vol 41 (5) ◽  
pp. 566-571 ◽  
Author(s):  
Katherine Debulis ◽  
Alexander M. Klibanov
Keyword(s):  
Enzymatic Activity ◽  
Organic Solvents

Improved enzymatic determination of total cholesterol in tissues.

1983 ◽  
Vol 29 (1) ◽  
pp. 166-168 ◽  
Author(s):  
B H Cho
Keyword(s):  
Enzymatic Activity ◽  
Total Cholesterol ◽  
Aqueous Medium ◽  
Organic Solvents ◽  
Tissue Lipid ◽  
Improved Method ◽  
Enzymatic Determination

Abstract In this improved method for rapid enzymatic determination of total cholesterol, the lipid extracts from tissues are dissolved in an equal volume of peroxide-free dioxane/isopropanol (50/50 by vol) solution, and are reacted directly with the aqueous enzymatic reagent, without further treatment. The presence of organic solvents, such as dioxane and isopropanol, does not interfere with enzymatic activity. This simpler procedure eliminates the tedious solubilization of tissue lipid extracts into an aqueous medium. The method is reproducible, and results correlate well with those by a chemical (FeCl3/H2SO4) method.

A Method for the Colorimetric Determination of β-Glucuronidase in Urine, Serum, Tissue; Assay of Enzymatic Activity in Health and Disease

1959 ◽  
Vol 36 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Julius A. Goldbarg ◽  
Esteban P. Pineda ◽  
Benjamin M. Banks ◽  
Alexander M. Rutenburg
Keyword(s):  
Enzymatic Activity ◽  
Colorimetric Determination ◽  
Health And Disease ◽  
Urine Serum

Isolation of Antithrombin III from Normal and α1-Antitrypsin-Deficient Human Plasma

1977 ◽  
Vol 38 (02) ◽  
pp. 0475-0485 ◽  
Author(s):  
Anna D. Borsodi ◽  
Ralph A. Bradshaw
Keyword(s):  
Enzymatic Activity ◽  
Isoelectric Focusing ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Antithrombin Activity ◽  
Bovine Trypsin ◽  
Normal Plasma ◽  
Antitrypsin Deficiency ◽  
Simplified Procedure ◽  
Stimulation Of

SummaryThe plasma of individuals, hetero- or homozygous for α1-antitrypsin deficiency, contains greatly decreased amounts of antithrombin activity as assayed against factor Xa. However, heparin stimulation of the residual antithrombin activity is observed, which is comparable to that of normal plasma. Antithrombins isolated from both normal and α1-antitrypsin deficient plasma by a simplified procedure are indistinguishable in both properties and yields. The microheterogeneity observed on isoelectric focusing of both preparations can be eliminated by treatment with neuraminidase. Neither purified human antithrombin nor α1-antitrypsin, when assayed against bovine trypsin, is stimulated by heparin. These results clearly establish the unique natures of antithrombin and α1-antitrypsin and show that about 75% of the antithrombin activity measured in normal plasma is due to α1-antitrypsin. Estimates of anti thrombin III activity in normal plasma by assays dependent on enzymatic activity can probably be obtained only in the presence of heparin.

Mechanism of Inhibitory Action on Platelet Activation of a Phospholipase A2 Isolated from Lachesis muta (Bushmaster) Snake Venom

1997 ◽  
Vol 78 (05) ◽  
pp. 1372-1380 ◽  
Author(s):  
André L Fuly ◽  
Olga L T Machado ◽  
Elias W Alves ◽  
Célia R Carlinis
Keyword(s):  
Platelet Aggregation ◽  
Enzymatic Activity ◽  
Phospholipase A2 ◽  
Inhibitory Activity ◽  
Thermal Inactivation ◽  
Anticoagulant Activity ◽  
Gel Filtration ◽  
Apparent Molecular Weight ◽  
Crude Venom ◽  
Lachesis Muta

SummaryCrude venom from Lachesis muta exhibited procoagulant, proteolytic and phospholipase A2 activities. A phospholipase A2, denoted LM-PLA2 was purified from L. muta venom to homogeneity, through a combination of chromatographic steps involving gel-filtration on Sephacryl S-200 HR and reverse phase chromatography on a C2/C18 column. LM-PLA2 presented a single polypeptide chain with an isoelectric point at pH 4.7 and apparent molecular weight of 17 kDa. Partial aminoacid sequence indicated a high degree of homology for LM-PLA2 with other PLA2 from different sources.LM-PLA2 displayed a potent enzymatic activity as measured by indirect hemolysis of red blood cells but it was neither lethal when injected i.p. into mice nor did it present anticoagulant activity. Furthermore, LM-PLA2 displayed a moderate inhibitory activity on the aggregation of rabbit platelets induced by low levels of ADP, thrombin and arachidonate. In contrast, platelet aggregation induced by high doses of collagen was strongly inhibited by LM-PLA2 as well as ATP-release. Treatment of the protein with p-bromophenacyl bromide or 2-mercapto-ethanol, as well as thermal inactivation studies, suggested that the platelet inhibitory effect of LM-PLA2 is dependent on its enzymatic activity. Thus, the platelet inhibitory activity of LM-PLA2 was shown to be dependent on the hydrolysis of plasma phospholipids and/or lipoproteins, most probably those rich in phosphatidylcholine. Surprisingly, lyso-phosphatidylcholine released by LM-PLA2 from plasma was shown to preferentially inhibited collagen-induced platelet aggregation, in contrast to other PLA2s, whose plasma hydrolytic products indistinctly affect platelet’s response to several agonists.

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