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.

Model proteolysis of β-casein by immobilized trypsin

1979 ◽  
Vol 46 (2) ◽  
pp. 223-226 ◽  
Author(s):  
Ernst H. Reimerdes
Keyword(s):  
Quantitative Determination ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Model System ◽  
Transmission Measurement ◽  
Electrophoretic Patterns ◽  
Immobilized Trypsin ◽  
Pure Protein ◽  
The Individual

SUMMARYThe enzymic degradation of β-casein by immobilized trypsin is described and its use as a model system to study proteolytic reactions which occur in milk during processing is examined. Quantitative determination of proteolysis can be obtained by densitometric transmission measurement of patterns obtained by polyacrylamide-gel electrophoresis. Staining properties of some of the individual components in the electrophoretic patterns were determined by calibration with pure protein and peptide preparations. The isolation of pure β- and γ-caseins and the preparation of several forms of immobilized trypsin are outlined.

QUANTITATIVE MEASUREMENT OF METAL ION CONCENTRATION OF PROTEINS SEPARATED BY ELECTROPHORESIS

1996 ◽  
Vol 06 (01n02) ◽  
pp. 215-225 ◽  
Author(s):  
G. WEBER ◽  
D. STRIVAY ◽  
C. MENENDEZ ◽  
B. SCHOEFS ◽  
M. BERTRAND
Keyword(s):  
Content Analysis ◽  
Quantitative Determination ◽  
Gel Electrophoresis ◽  
Metal Ion ◽  
Metal Content ◽  
Quantitative Measurement ◽  
Polyacrylamide Gel Electrophoresis ◽  
Ion Concentration ◽  
X Ray

This communication is devoted to nature determination and quantification by PIXE of metals contained in proteins after their separation by PolyAcrylamide Gel Electrophoresis (PAGE). After the electrophoresis, the gel is dried and each track is scanned with a 2.5 MeV proton beam which triggers metal X-ray fluorescence and then, allows to determine the type of metals contained in an electrophoretic band. For quantitative determination of the amount of the metal contained inside the band, the characteristic X-ray peak area is compared with those obtained with polyacrylamide gels doped with the same metal. The normalization has been achieved by using RBS measurements on the gel itself. The procedure presented seems to be a very useful multielementary method for the metal content analysis and for the determination of the metal amounts inside proteins after their separation by electrophoresis. Furthermore it allows to check if metals remain bound to proteins.

scholarly journals Purification and some properties of arylsulphatases A and B from rabbit kidney cortex

1977 ◽  
Vol 165 (1) ◽  
pp. 127-134 ◽  
Author(s):  
J J Helwig ◽  
A A Farooqui ◽  
C Bollack ◽  
P Mandel
Keyword(s):  
Ascorbic Acid ◽  
Gel Electrophoresis ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Chromatography Method ◽  
Arylsulphatase A ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Arylsulphatases A and B (EC 3.1.6.1) of rabbit kidney cortex were purified 5250- and 7720-fold respectively by a multiple-column-chromatography method. The specific activity toward 4-nitrocatechol sulphate was 42mumol/min per mg for arylsulphatase A and 62 mumol/min per mg for arylsulphatase B. Each enzyme migrated as a single band on polyacrylamide-gel electrophoresis, and the enzyme activity corresponded to the band of protein on the gel. The rate of hydrolysis of ascorbic acid 2-sulphate by arylsulphatase A was three times that for cerebroside 3-sulphate. Arylsulphatase B hydrolysed UDP-N–acetylgalactosamine 4-sulphate and glucosamine 4,6-disulphate, but not galactosamine 6-sulphate.

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