The action of rennets on the caseins: I. Rennin action on β-casein-B in solution

Creamer, Lawrence K.; Mills, O. E.; Richards, Edward

doi:10.1017/s0022029900019385

Cited by 40 publications

(24 citation statements)

References 15 publications

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“…Other bonds, one in a sl -casein (Hill et at. 1974) and 3 in /?-casein (Creamer et al 1971;Pelissier et al 1974), are also hydrolysed at high rates by these enzymes. At higher concentrations, chymosin and pepsins can hydrolyse, in vitro, a number of bonds in the different caseins (Pelissier el al.…”

mentioning

confidence: 98%

Kinetic studies ofin vivodigestion of bovine unheated skim-milk proteins in the rat stomach

Miranda

Pélissier

1983

Journal of Dairy Research

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SummaryThein vivoaction of gastric proteinases on bovine milk proteins was studied in rats fed with skim-milk, by analysing gastric contents after 30, 60 and 240 min of digestion. Gastric proteolysis was already marked after 30 min of digestion and liberated a large number of peptides with different molecular weights. αs1-Casein and β-casein were still the main components of the stomach contents together with α-lactalbumin and β-lactoglobulin, which were little degraded, even after 240 min of digestion. A statistical analysis (multivariate method), made on several parameters (such as pH, N, and NPN) showed changes in the stomach contents during the digestion. The amino acid composition of the protein fraction was close to that of the diet, whilst that of the non-protein fraction was very different, being between the amino acid composition of the endogenous proteins and that of the diet.

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confidence: 98%

Kinetic studies ofin vivodigestion of bovine unheated skim-milk proteins in the rat stomach

Miranda

Pélissier

1983

Journal of Dairy Research

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“…wts of about 35 000: it would therefore be expected that if the casein micelle has an open, sponge-like structure, as suggested by Gamier & Ribadeau Dumas (1970), the degree of aggregation should not influence rennin proteolysis either. Simple aggregation is unlikely to account for the marked difference in susceptibility of micellar components to rennin and carboxypeptidase because: (1) /?-casein has 3 rennin-susceptible bonds, all toward the C-terminal (Creamer et al 1971), while a si -casein has 6-7 renninsusceptible bonds , and if the C-terminal is free for carboxypeptidase one would expect at least some of the rennin-susceptible bonds to be available, and…”

Section: Resultsmentioning

confidence: 99%

Casein micelle structure: susceptibility of various casein systems to proteolysis

Fox

Guiney

1973

Journal of Dairy Research

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The susceptibility of the components of various casemate systems (skimmilk, yff-casein-depleted milks, colloidal phosphate-free (CPF) milk, sodium caseinate and isolated y?-casein) to proteolysis was investigated. Isolated a si -and /?-caseins were quite susceptible to proteolysis, but their susceptibility decreased in heterogeneous soluble systems and even more so in heterogeneous aggregated systems. In skim-milk and /?-casein-depleted milks only about 50 % of both a 81 -and /?-casein was hydrolysable by high levels of rennin, and in CPF milk all a si -and 70 % of the /S-casein was hydrolysable. It is suggested that about 50 % of micellar /?-casein is firmly fixed within the micelle and is unavailable for proteolysis, while the remainder can dissociate from the micelle on cooling and is then readily hydrolysable.The compatibility of the data with the various published models of the casein micelle is discussed, and a modification of Rose's (1969) model is proposed.

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“…Creamer et al (27) studied the action of milk-clotting enzyme chymosin (rennin) on β-casein by zonal column chromatography at neutral pH. They found that chymosin preferably splits off a C-terminal fragment from β-casein with a molecular weight of approximately 2000 Da.…”

Section: Characterization Of the Protein Fragment P-cn-(/l-192)mentioning

confidence: 99%

Importance of C-Terminal Region of Bovine β-Casein

2006

ACS Symposium Series

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Bovine β-casein (β-CN) with the C-terminal truncated by chymosin digestion, 1-192 fragment (β-CN-(f1-192)), was examined using circular dichroism (CD) under various temperature and solvent conditions. The effect of C-terminal deletion on the structure and stability of the parent protein, β -casein (β-CN), is analyzed and discussed. Analytical ultracentrifugation results showed reduced degree of self -association in β-CΝ-(f1-192) compared to whole β-casein. CONTIN/LL analysis of the CD data revealed clear changes in the overall secondary structural content in β-CΝ-(f1-192) in the temperature range studied (5 to 70°C). Results obtained in this work suggest significant secondary structure disruption of β-casein upon its C-terminal deletion. It has been shown that 80% trifluoroethanol (TFE) at low temperatures (≤ 25°C) can effectively induce α-helical content in β-CΝ-(f1-192), to the same level as that of β-CN. In addition, sodium dodecyl sulfate (SDS) at greater than micellar concentration is capable of refolding β-CΝ-(f1-192). Temperature dependence of these induced structures was also studied. Furthermore, binding experiments with the common hydrophobic probe-8-Anilino-1-naphthalene sulfonate (ANS) illustrated that β-CN -(f1-192) is nearly incapable of binding to ANS. These results clearly demonstrated that the tail peptide, β-CN-(f193-209) is important in maintaining the hydrophobic core of β-CN.U.S. government work.

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The action of rennets on the caseins: I. Rennin action on β-casein-B in solution

Cited by 40 publications

References 15 publications

Kinetic studies ofin vivodigestion of bovine unheated skim-milk proteins in the rat stomach

Kinetic studies ofin vivodigestion of bovine unheated skim-milk proteins in the rat stomach

Casein micelle structure: susceptibility of various casein systems to proteolysis

Importance of C-Terminal Region of Bovine β-Casein

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