scholarly journals THE DIFFUSION COEFFICIENT OF CRYSTALLINE TRYPSIN

1933 ◽  
Vol 16 (5) ◽  
pp. 795-800 ◽  
Author(s):  
Henry W. Scherp
Keyword(s):  
Diffusion Coefficient ◽  
Magnesium Sulfate ◽  
Proteolytic Activity ◽  
Adsorption Complex ◽  
Protein Nitrogen ◽  
Chemical Combination ◽  
Molecular Radius

The diffusion coefficient of crystalline trypsin in 0.5 saturated magnesium sulfate at 5°C. is 0.020 ±0.001 cm.2 per day, corresponding to a molecular radius of 2.6 x 10–7 cm. The rate of diffusion of the proteolytic activity is the same as that of the protein nitrogen, indicating that these two properties are held together in chemical combination and not in the form of an adsorption complex.

scholarly journals CRYSTALLINE TRYPSIN

1932 ◽  
Vol 16 (2) ◽  
pp. 295-311 ◽  
Author(s):  
John H. Northrop ◽  
M. Kunitz
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Magnesium Sulfate ◽  
Carboxyl Groups ◽  
Native Protein ◽  
Optimum Stability ◽  
Optimum Ph ◽  
Tryptic Activity ◽  
Pressure Measure ◽  
Molecular Radius

A method is described for isolating a crystalline protein of high tryptic activity from beef pancreas. The protein has constant proteolytic activity and optical activity under various conditions and no indication of further fractionation could be obtained. The loss in activity corresponds to the decrease in native protein when the protein is denatured by heat, digested by pepsin, or hydrolyzed in dilute alkali. The enzyme digests casein, gelatin, edestin, and denatured hemoglobin, but not native hemoglobin. It accelerates the coagulation of blood but has little effect on the clotting of milk. It digests peptone prepared by the action of pepsin on casein, edestin or gelatin. The extent of the digestion of gelatin caused by this enzyme is the same as that caused by crystalline pepsin and is approximately equivalent to tripling the number of carboxyl groups present in the solution. The activity of the preparation is not increased by enterokinase. The molecular weight by osmotic pressure measure is about 34,000. The diffusion coefficient in ½ saturated magnesium sulfate at 6°C. is 0.020 ±0.001 cm.2 per day, corresponding to a molecular radius of 2.6 x 10–7 cm. The isoelectric point is probably between pH 7.0 and pH 8.0. The optimum pH for the digestion of casein is from 8.0–9.0. The optimum stability is at pH 1.8.

Proteolytic activity in UHT-sterilized milk

1979 ◽  
Vol 46 (2) ◽  
pp. 227-229 ◽  
Author(s):  
Cesare Corradini ◽  
Paola Panini Pecis
Keyword(s):  
Proteolytic Activity ◽  
Gel Formation ◽  
Casein Micelles ◽  
Protein Nitrogen ◽  
Sterilized Milk ◽  
Control Samples

SUMMARYThe proteolytic activity in UHT-sterilized milk of a proteinase-containing fraction, prepared from the milk, is reported. The proteinase fraction was isolated from casein micelles as described by Reimerdes & Klostermeyer (1974).The fraction was added to UHT milks and the proteolysis in the samples, measured as the liberation of non-protein nitrogen, compared with that in control samples without added proteinases. The increase in proteolytic activity and deterioration in samples containing added proteinases indicated that an enzyme process occurred in UHT-sterilized milk which could influence gel formation.

scholarly journals CRYSTALLINE PEPSIN

1930 ◽  
Vol 13 (6) ◽  
pp. 739-766 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Solid Solution ◽  
Diffusion Coefficient ◽  
Proteolytic Activity ◽  
Optical Activity ◽  
Pure Substance ◽  
Peptic Activity ◽  
Salt Solutions

A method is described for the preparation of a crystalline protein from commercial pepsin preparations which has powerful peptic activity. The composition, optical activity, and proteolytic activity of this protein remain constant through seven successive crystallizations. No evidence for the presence of a mixture or of a solid solution is found in a study of the solubility of the protein in a series of different salt solutions, nor from the diffusion coefficient or from the rate of inactivation. These results indicate that the material is a pure substance or possibly a solid solution of two or more substances having nearly the same solubility in all the various solvents studied. It seems reasonable to conclude from these experiments that the possibility of a mixture must be limited to a mixture of proteins, so that the conclusion seems justified that pepsin itself is a protein.

207. Protein metabolism and acid production by the lactic acid bacteria in milk. Influence of yeast extract and chalk

1939 ◽  
Vol 10 (1) ◽  
pp. 20-34 ◽  
Author(s):  
M. Braz ◽  
L. A. Allen
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Proteolytic Activity ◽  
Yeast Extract ◽  
Protein Metabolism ◽  
Acid Production ◽  
Single Species ◽  
Soluble Nitrogen ◽  
Protein Breakdown ◽  
Protein Nitrogen

Though the lactic acid bacteria are recognized primarily as saccharolytic, several workers have recorded observations on their slow proteolytic activity. Von Freudenreich(1) was the first to record the fact that cultures of these organisms in milk, to which chalk had been added to neutralize the acidity, formed appreciable amounts of soluble nitrogen, and these findings were confirmed by Orla-Jensen (2), Barthel(3), and Barthel & Sandberg(4). Anderegg & Hammer (5), in a study of a large number of strains ofStr. Lactis, found an increase in soluble nitrogen in some cases and a decrease in others, while occasionally the same strain differed in different tests. In general, cultures which clotted rapidly were more inclined to proteolysis than those which were slower in forming acid.Str. citrovorusandStr. paracitrovorusdid not cause protein breakdown. Addition of 0·3% peptone to the milk tended to retard proteolysis or to increase negative values while addition of chalk resulted in more extensive proteolysis. Barthel & Sadler (6) found that starters consisting of mixed cultures of streptococci produced more extensive proteolysis than single species, indicating a symbiotic effect. Sherwood & Whitehead (7) tested the proteolytic powers of several strains ofStr. cremorisin chalk milk cultures and found some active and some comparatively inactive. Two strains appear to have formed surprisingly large amounts of non-protein nitrogen. In general they found that acid-producing power was linked with proteolytic power.

scholarly journals CRYSTALLINE PEPSIN

1933 ◽  
Vol 16 (4) ◽  
pp. 615-623 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Gastric Mucosa ◽  
Magnesium Sulfate ◽  
Gastric Juice ◽  
Proteolytic Activity ◽  
Optical Activity ◽  
Specific Activity ◽  
Crystalline Form ◽  
High Proteolytic Activity ◽  
Related Proteins

1. A method has been described for isolating a crystalline protein with high proteolytic activity from bovine gastric juice by means of precipitation with magnesium sulfate and fractionation of the precipitate with acetone and magnesium sulfate. 2. The crystalline protein obtained in this way has the same crystalline form, optical activity, and specific activity, as determined by a number of methods, as does the crystalline protein previously isolated from swine gastric mucosa. 3. The solubility of the two preparations, however, is additive so that they are different although very closely related proteins.

The development of the digestive system of the young animal V. The development of rumen function in the young lamb

1961 ◽  
Vol 57 (2) ◽  
pp. 271-278 ◽  
Author(s):  
D. M. Walker ◽  
Gwen J. Walker
Keyword(s):  
Proteolytic Activity ◽  
Digestive System ◽  
Amylase Activity ◽  
Young Animal ◽  
Enzymic Activity ◽  
Protein Nitrogen ◽  
Adult Sheep

1. A total of twenty-one Merino lambs varying in age from 2 to 11 weeks were slaughtered.2. The enzymic activity of their rumen contents was measured on a variety of carbohydrates and on protein.3. Enzymic activity was expressed as mg. carbohydrate hydrolysed/mg. protein nitrogen/hour.4. When compared with the rumen contents of adult sheep, lactase and proteolytic activity decreased with age; maltase, sucrase and fructanase activity increased; amylase activity decreased from 2 to 11 weeks though adult values were similar to those of the 2-week-old lamb.5. The rumen contents of the lamb were as efficient as those of the adult sheep in their ability to hydrolyse a wide variety of carbohydrates and protein.

Effect of breed on proteolysis and free amino acid profiles of dry-cured loin during processing

2019 ◽  
Vol 59 (6) ◽  
pp. 1161 ◽  
Author(s):  
Eva Salazar ◽  
José M. Cayuela ◽  
Adela Abellán ◽  
Luis Tejada
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Proteolytic Activity ◽  
Free Amino Acids ◽  
Free Amino ◽  
Processing Time ◽  
Point Of View ◽  
Protein Nitrogen ◽  
Amino Acid Profiles

Non-protein nitrogen (NPN) and free amino acids (FAA) were analysed in dry-cured loin obtained from the native pig breed Chato Murciano (CM) during processing. In addition, a comparison was drawn between the NPN and FAA values obtained in CM and those obtained in dry-cured loin from a modern crossbreed pig genotype (CG) at commercialisation times (between 30 and 60 days of processing). Processing time affected NPN, total FAA concentration, and all FAA studied, except arginine, histidine and lysine. The breed affected both NPN and total FAA, as superior values were observed in CM at Day 30. From this moment onward, proteolysis was more intense in CG than in CM. At Day 30, the concentration of most amino acids, except for lysine and arginine, was higher in CM. Whereas the concentration of all amino acids, except serine, histidine and methionine + tryptophan, was higher in CG at Day 60. The breed affected proteolytic activity in dry-cured loin. The results suggested that, from the point of view of proteolysis, the optimum processing time for CM dry-cured loin is 45 days.

Relation Between Proteolytic Activity and Protein Nitrogen of Canine Pancreatic Juice

1955 ◽  
Vol 183 (3) ◽  
pp. 495-509 ◽  
Author(s):  
S. A. Komarov ◽  
Herman Siplet ◽  
Harry Shay ◽  
Paul H. Guth
Keyword(s):  
Proteolytic Activity ◽  
Pancreatic Juice ◽  
Protein Nitrogen

IV. PROTEOLYTIC ACTIVITY1

1971 ◽  
Vol 34 (3) ◽  
pp. 124-128 ◽  
Author(s):  
Antonieta Gaddi Angeles ◽  
E. H. Marth
Keyword(s):  
Bacillus Cereus ◽  
Microbial Activity ◽  
Proteolytic Activity ◽  
Lactobacillus Casei ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Delbrueckii ◽  
Protein Nitrogen ◽  
Colorimetric Measurement ◽  
Labor Consuming

Three methods were examined for their suitability to measure proteolysis brought about by microbial activity in soymilk. The Anson (or Hull) method, a colorimetric measurement of tyrosine and tryptophan, was not able to measure changes detectable by other methods and hence did not appear applicable for this work. Determination of non-protein nitrogen (NPN) to follow proteolytic changes in soymilk was feasible but was time- and labor-consuming. Dye-binding methods were found most workable. Lactobacillus delbrueckii and Streptococcus thermophilus exhibited proteolytic activity in soymilk but Lactobacillus casei did not. Two other microorganisms, Bacillus cereus and Micrococcus conglomeratus, and rennet were comparatively more proteolytic in soymilk than the lactic cultures.

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