The action of rennin on casein The disruption of the k-casein complex

Beeby, R.; Nitschmann, Hs. (1963). The action of rennin on casein The disruption of the k-casein complex. Journal of dairy research, 30(1), pp. 7-16. Cambridge University Press 10.1017/S0022029900011201

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Approximately 30% of the nitrogen of κ-casein was soluble at pH 4·7 after the protein had been treated with rennin at pH 7 while approximately 10% was soluble in 12% trichloroacetic acid (TCA). The material soluble in 12% TCA appeared at a slower rate initially than did the nitrogen soluble at pH 4·7 but as the reaction proceeded it was released more rapidly.

Treating κ-casein with urea, or repeated precipitation of the protein at pH 4·7, caused the formation of material insoluble at pH 7, apparently para-κ-casein. Both treatments appeared to free the same soluble fraction as does rennin acting in low concentration or for a short time.

Low concentrations of rennin (0·07 μg/ml) released only part of the available soluble nitrogen from 2% solutions of whole casein at pH 7. Heating the reaction mixture appeared to restore the casein complex, the restoration being less complete the longer the reaction had proceeded.

It is suggested that κ-casein is not a single protein but a complex, and that the action of rennin is first to open the secondary bonds responsible for the stability of this complex.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)
05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH)




Cambridge University Press




Marceline Brodmann

Date Deposited:

09 Jul 2020 09:05

Last Modified:

02 Aug 2020 00:31

Publisher DOI:





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