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Comparison of the specificity and kinetic properties of 3 milk-clotting enzymes

Published online by Cambridge University Press:  01 June 2009

Gizella Kovács-Proszt  and
T. Sanner
Gizella Kovács-Proszt
Affiliation:
Norsk Hydro's Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, Oslo, Norway
T. Sanner
Affiliation:
Norsk Hydro's Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, Oslo, Norway
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Summary

The biochemical properties of rennin purified from calf stomach, Mucor pusillus and Endothia parasitica have been compared.

The specificities of the enzymes have been studied by separating by disk-gel electrophoresis the macropeptides released on incubation with acid casein and κ-casein. The products formed on incubation with rennin from calf stomach and M. pusillus showed some similarity although several bands were found which did not correspond to one another. The products formed with rennin from E. parasitica differed considerably from those with the 2 other enzymes.

The kinetic properties of the enzymes have been investigated in stopped-flow experiments on the enzyme-induced aggregation of κ-casein. The aggregation has been characterized by 2 parameters—the lag time prior to the increase in extinction and the maximum rate of change in extinction during aggregation.

The specific activity measured from the inverse value of the lag time was under optimal conditions nearly 2·5 times higher for rennin from calf stomach than for rennin from the 2 micro-organisms. The fact that with increasing enzyme concentration the maximum rate of change of extinction during aggregation was identical for all 3 enzymes indicates that the same product is responsible for the formation of the aggregates. The data suggest that the Km value for the aggregation of κ-casein by the enzymes is about 100 times smaller than Km for the proteolytic activity of calfstomach rennin on κ-casein. The possibility is suggested that the high specificity of the enzymes in milk clotting is due to the very low Km values for the peptide bond modifications involved in the formation of para-κ-casein, the first enzymic step in the clotting of milk.

Type
Research Article
Information
Journal of Dairy Research , Volume 40 , Issue 2 , June 1973 , pp. 263 - 272
Copyright
Copyright © Proprietors of Journal of Dairy Research 1973

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References

REFERENCES

Arima, K., Iwasaki, S. & Tamura, G. (1967). Agricultural and Biological Chemistry 31, 540.Google Scholar
Arima, K., Yu, J., Iwasaki, S. & Tamura, G. (1968). Applied Microbiology 16, 1727.CrossRefGoogle Scholar
Armstrong, C. E., Mackinlay, A. G., Hill, R. J. & Wake, R. G. (1967). Biochimica et Biophysica Acta 140, 123.CrossRefGoogle Scholar
Cheeseman, G. C. (1962). Journal of Dairy Research 29, 163.CrossRefGoogle Scholar
Cleland, W. W. (1970). In The Enzymes, 3rd edn 2, 40. (Ed. Boyer, P. D..) New York: Academic Press.Google Scholar
El-Negoumy, A. M. (1968). Journal of Dairy Science 51, 1013.CrossRefGoogle Scholar
Hipp, N. J., Groves, M. L., Custer, J. H. & McMeekin, T. L. (1950). Journal of the American Chemical Society 72, 4928.CrossRefGoogle Scholar
Jollès, J., Alais, C. & Jollès, P. (1968). Biochimica et Biophysica Acta 168, 591.CrossRefGoogle Scholar
Kawai, M. & Mukai, N. (1970). Agricultural and Biological Chemistry 34, 159.Google Scholar
Lawrence, R. C. & Creamer, L. K. (1969). Journal of Dairy Research 36, 11.CrossRefGoogle Scholar
Lowry, O. H., Rosebrough, N. J., Farr, A. L. & Randall, R. J. (1951). Journal of Biological Chemistry 193, 265.CrossRefGoogle Scholar
Mackinlay, A. G. & Wake, R. G. (1964). Biochimica et Biophysica Acta 93, 378.CrossRefGoogle Scholar
McKenzie, H. A. & Wake, R. G. (1961). Biochimica et Biophysica Acta 47, 240.CrossRefGoogle Scholar
Mocquot, G. & Garnier, J. (1965). Journal of Agricultural and Food Chemistry 13, 414.CrossRefGoogle Scholar
Sanner, T. & Kovács-Proszt, G. (1973). Biochimica et Biophysica Acta 303, 68.CrossRefGoogle Scholar
Sardinas, J. L. (1968). Applied Microbiology 16, 248.CrossRefGoogle Scholar
Wake, R. G. (1959). Australian Journal of Biological Sciences 12, 479.CrossRefGoogle Scholar