Succinyl amphiphiles

All of the data from Table II indicate that, under the unconventional conditions intentionally set in the present study, papain can catalyze the aminolysis of the ES intermediate that probably occurs from succinylated asi-casein (substrate) and papain (enzyme) by L-norleucine n-dodecyl ester (nucleophile), with formation of a surface-active 20,000-dalton product to which this lipophilic nucleophile is attached covalently as illustrated in Figure 1. The observed amphiphilic function of the 20,000-dalton product is probably a result of the formation of a localized hydro-... 

In order to produce the amphoteric protein-based surfactant, the incorporation of lipophilic amino acid ester was attempted using the one-step method of plastein reaction with papain at pH 9. In a system containing succinylated ttsi-casein as a protein substrate and luecine n-dodecyl ester as a lipophile, the peptide bond between Phe and Tyr of casein was first hydrolyzed, and this is followed by the incorporation of luecine n-dodecyl ester at the same position, forming a new C-terminus [34]. The structure of the macropeptide with respect to the distribution of hydrophilic amino acid residues is shown in Fig. 4 [29,34]. Amphiphilic structure consisting of hydrophilic protein portion and lipophilic luecine n-dodecyl ester was clearly demonstrated. 

As amply discussed in Chapter 2 [Secs. Ill, IV], proteins from different sources can be modified to produce a wide variety of PBS. Some of the techniques used in protein modification have been indicated in Chapter 5 [Secs. II-VII], with reference to PBS produced via a degradation process such as proteolysis and deamidation, in addition to the cases of the surfactants produced by covalent attachment of nonprotein moieties. Enzymatic modification of proteins with specific reference to food application has been discussed in Chapter 1, Section II.B. Briefly, it was hypothesized that by reacting a hydrophilic protein as the substrate with highly hydrophobic amino acid ester as the nucleophile, a product with amphiphilic properties would result from the localized regions of hydrophobicity [76]. To obtain adequately hydrophilic proteins as substrates, succinylation could be used to modify the proteins prior... 

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