scholarly journals A rapid direct assay for the determination of the separate activities of the three arylsulphatases of Aspergillus oryzae

1977 ◽  
Vol 166 (3) ◽  
pp. 411-413 ◽  
Author(s):  
G R J Burns ◽  
C H Wynn
Keyword(s):  
Phenolic Compounds ◽  
Aspergillus Oryzae ◽  
Substrate Specificities ◽  
Direct Assay ◽  
Assay Procedure ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Potential Use

1. The three arylsulphatases of Aspergillus oryzae exhibit pronounced kinetic differences and substrate specificities. Arylsulphatase I hydrolyses all substrates tested, whereas arylsulphatase III will not hydrolyse tyrosine O-sulphate or phenolphthalein disulphate. Arylsulphatase II does not hydrolyse p-nitrophenyl sulphate or phenolphthalein disulphate at appreciable rates in the absence of added phenolic compounds. Phenols such as tyramine increase the rate of hydrolysis of these substances by this enzyme 1000-fold. At pH 6.9 arylsulphatase I exhibits an apparent Km of 0.1 mM for p-nitrophenyl sulphate, whereas the Km of arylsulphatase III for this substrate is 1 mM. 2. These differences were utilized to develop an assay procedure which can be used to determine the separate activities of the three enzymes present in mixtures. This assay has potential use as a means of examining the relative activities of the three enzymes in investigations of the differences in the mechanisms regulating their synthesis.

Polarographic study of hydrolysis of [8-lysine]vasopressin and its derivatives with blood serum of pregnant women

1980 ◽  
Vol 45 (4) ◽  
pp. 1099-1108 ◽  
Author(s):  
Mikuláš Chavko ◽  
Michal Bartík ◽  
Evžen Kasafírek
Keyword(s):  
Blood Serum ◽  
Pregnant Women ◽  
Degree Of Hydrolysis ◽  
Polarographic Study ◽  
Ph Optimum ◽  
Lysine Vasopressin ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Vasopressin Analogues

A polarographic study of the hydrolysis of [8-lysine]vasopressin and some hormonogens of the vasopressin series with the blood serum of women in the last week of pregnancy was studied. The dependence of hydrolysis on pH (pH optimum: 7.4-7.50, substrate concentration (Km 1.2 . 10-5M), pH stability and thermal stability were determined. The rate of hydrolysis of individual vasopressin analogues decreases in the order: [8-lysine]vasopressin > Nα-glycyl-prolyl[8-lysine]-vasopressin > Nα-leucyl-[8-lysine]vasopressin > Nα-alanyl-[8-lysine]vasopressin > Nα-phenyl alanyl-[8-lysine]vasopressin > Nα-diglycyl-[8-lysine]vasopressin > Nα-prolyl-[8-lysine]vasopressin > Nα-triglycyl-[8-lysine]vasopressin > Nα-sarcosyl-glycyl-[8-lysine]vasopressin. The degree of hydrolysis gradually increases to a multiple with the length of the pregnancy in consequence of the presence of oxytocine. However, vasopressin is also hydrolysed to a small extent with the enzymes from the blood sera of non-pregnant women. Under similar analytical conditions oxytocin was not hydrolysed with the sera of non-pregnant women and therefore oxytocin is a more suitable substrate than vasopressin for polarographic determination of serum oxytocinase.

scholarly journals Evidence for the regulation of guinea-pig heart microsomal phosphatidylcholine-hydrolysing phospholipase A1 by guanosine 5′-[γ-thio]triphosphate

1992 ◽  
Vol 288 (3) ◽  
pp. 965-968 ◽  
Author(s):  
K Badiani ◽  
X Lu ◽  
G Arthur
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Guinea Pig ◽  
Molecular Species ◽  
Inhibitory Effect ◽  
Phospholipase A1 ◽  
Guinea Pig Heart ◽  
Substrate Specificities ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

We have recently characterized lysophospholipase A2 activities in guinea-pig heart microsomes and postulated that these enzymes act sequentially with phospholipases A1 to release fatty acids selectively from phosphatidylcholine (PC) and phosphatidylethanolamine, thus providing an alternative route to the phospholipase A2 mode of release. In a further investigation of the postulated pathway, we have characterized the PC-hydrolysing phospholipase A1 in guinea-pig heart microsomes. Our results show that the enzyme may have a preference for substrates with C16:0 over C18:0 at the sn-1 position. In addition, although the enzyme cleaves the sn-1 fatty acid, the rate of hydrolysis of PC substrates with C16:0 at the sn-1 position was influenced by the nature of the fatty acid at the sn-2 position. The order of decreasing preference was C18:2 > C20:4 = C18:1 > C16:0. The hydrolyses of the molecular species were differentially affected by heating at 60 degrees C. An investigation into the effect of nucleotides on the activity of the enzyme showed that guanosine 5′-[gamma-thio]triphosphate (GTP[S]) inhibited the hydrolysis of PC by phospholipase A1 activity, whereas GTP, guanosine 5′-[beta-thio]diphosphate (GDP[S]), GDP, ATP and adenosine 5′-[gamma-thio]triphosphate (ATP[S]) did not affect the activity. The inhibitory effect of GTP[S] on phospholipase A1 activity was blocked by preincubation with GDP[S]. A differential effect of GTP[S] on the hydrolysis of different molecular species was also observed. Taken together, the results of this study suggest the presence of more than one phospholipase A1 in the microsomes with different substrate specificities, which act sequentially with lysophospholipase A2 to release linoleic or arachidonic acid selectively from PC under resting conditions. Upon stimulation and activation of the G-protein, the release of fatty acids would be inhibited.

Automated kinetic determination of angiotensin-converting enzyme in serum.

1984 ◽  
Vol 30 (6) ◽  
pp. 901-902 ◽  
Author(s):  
A Harjanne
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Previous Method ◽  
Converting Enzyme ◽  
Kinetic Determination ◽  
Assay Time ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Abstract In this automated kinetic modification of a previous method (Anal Biochem 95: 540-548, 1979) for determining angiotensin-converting enzyme (EC 3.4.15.1), 3-(2- furylacryloyl )-L- phenylalanylglycylglycine is used as the substrate. The change in absorbance at 340 nm is used to monitor hydrolysis of the substrate. The rate of hydrolysis is roughly threefold greater than with previously reported substrates, so assay time and sensitivity are improved.

Determination of the proportion of κ-casein hydrolysed by rennet on coagulation of skim-milk

1980 ◽  
Vol 47 (3) ◽  
pp. 351-358 ◽  
Author(s):  
Brian Chaplin ◽  
Margaret L. Green
Keyword(s):  
Quantitative Determination ◽  
Gel Electrophoresis ◽  
Time Course ◽  
Polyacrylamide Gel Electrophoresis ◽  
Skim Milk ◽  
Casein Micelle ◽  
Clotting Time ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

SummaryA method has been developed for quantitative determination of para-κ-casein, involving spectrophotometric scanning of stained protein bands following polyacrylamide gel electrophoresis. The rate of hydrolysis of κ-casein in skim-milk at pH 6·6 and 30 °C was compared with that in EDTA-treated skim-milk under the same conditions. This showed that at the visually observed clotting time, at least 90% of the total κ-casein in milk had been hydrolysed. The time course of the reaction was consistent with all the κ-casein molecules being hydrolysed with the same efficiency. The results strongly suggest that essentially all of the κ-casein in milk is equally accessible to rennet action. This is consistent with the casein micelle being porous, or having all the κ-casein on the surface.

Growth of Molds on Cheese Treated with Heat or Liquid Smoke

1993 ◽  
Vol 56 (11) ◽  
pp. 963-966 ◽  
Author(s):  
WILLIAM L. WENDORFF ◽  
WILLIAM E. RIHA ◽  
EMILY MUEHLENKAMP
Keyword(s):  
Phenolic Compounds ◽  
Aspergillus Oryzae ◽  
Cheddar Cheese ◽  
Heat Treatments ◽  
Mold Growth ◽  
Penicillium Roqueforti ◽  
Liquid Smoke ◽  
Penicillium Camemberti ◽  
Lag Period ◽  
Potential Use

Liquid smoke and heat treatments were evaluated for their potential use to inhibit growth of Aspergillus oryzae, Penicillium camemberti, and Penicillium roqueforti on Cheddar cheese. A. oryzae had a longer lag period and P. roqueforti grew faster radially on cheese heated at 42°C for 1 h than on unheated cheese. Mold growth on cheese heated at 24 and 33°C for 1 h was not significantly different from that on the unheated control. Liquid smoke applied to the surface of cheese totally inhibited growth of A. oryzae and significantly increased the lag period of P. camemberti and P. roqueforti. Of eight major phenolic compounds in smoke, only isoeugenol inhibited all three molds. P. camemberti was slightly inhibited by m-cresol and p-cresol, while A. oryzae was inhibited by guaiacol, 4-methylguaiacol, m-cresol, and p-cresol. Results of this study showed that phenolic compounds found in smoke are primarily responsible for inhibition of molds on smoked Cheddar cheese.

Separation and Micro Quantitative Determination of Dipterex and DDVP by Gas-Liquid Chromatography

1965 ◽  
Vol 48 (2) ◽  
pp. 374-379
Author(s):  
Abdel Rahman (Ali) El-Refai ◽  
Laura Giuffrida
Keyword(s):  
Liquid Chromatography ◽  
Simple Procedure ◽  
Gas Liquid Chromatography ◽  
Experimental Conditions ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Gas Chromatographic Separation ◽  
Sensitive Method ◽  
General Method

Abstract A simple, rapid, and sensitive method was required for the determination of Dipterex and DDVP in water and insecticidal formulations. Existing methods were found to he unsatisfactory. This paper describes a rapid method for the gas chromatographic separation and estimation of Dipterex and DDVP in macro and micro amounts. The sodium thermionic detector (STD) was used, and the GLC conditions are described. A general method for extraction of the two compounds from water solutions was developed and applied in studying the rate of hydrolysis of Dipterex and DDVP in river water. A simple procedure has been developed for analysis of formulations of Dipterex and DDVP. Several commercial formulations have been analyzed by this method with a precision of 1–2% obtained under experimental conditions.

Use of Chromogenic Substrate S-2251 for Determination of Plasminogen Activator in Rat Ovaries

1981 ◽  
Vol 46 (02) ◽  
pp. 507-510 ◽  
Author(s):  
H Shimada ◽  
T Mori ◽  
A Takada ◽  
Y Takada ◽  
Y Noda ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Enzymatic Reactions ◽  
Chromogenic Substrate ◽  
Assay Procedure ◽  
One Step ◽  
Reproducible Method ◽  
Plasmin Inhibitors ◽  
Endogenous Activity ◽  
Hydrolysis Of

SummaryA simple, specific and reproducible method for determination of plasminogen activator activity in rat ovaries has been developed by using the chromogenic substrate S-2251. The two steps of enzymatic reactions, i. e. activation of plasminogen and subsequent hydrolysis of the substrate was performed in one step incubation. A linear relationship was observed between the amount of chromogen produced and activator activity in the range of the optical density from 0.05 to 1.20 for 30 min’s incubation. Endogenous activity of non-specific proteases, plasmin or plasmin inhibitors which might be contained in rat ovaries turned out not to interfere with the specificity of a standardized assay procedure. Reproducibility was firmly established with coefficient of variation not exceeding 10%. Using this method, a marked increase followed by a drastic decrease in the activator activity was shown with rat ovaries around the time of ovulation after the injection of human chorionic gonadotropin.

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