PMID: 564944Apr 1, 1978Paper

Effect of reductive alkylation of the epsilon-amino group of lysyl redsidues of casein on its nutritive value in rats

The Journal of Nutrition
H S LeeR E Feeney


Casein epsilon-aminolysyl residues were converted to the methyl (and dimethyl), isopropyl or cyclopentyl derivatives in high yield with formaldehyde, acetone or cyclopentanone, respectively, in the presence of sodium borohydride. When incorporated into diets at 10% as the sole protein source, the chemically modified caseins failed to support growth of young rats. Methyl casein did, however, support limited growth after about 5 days. Plasma threonine levels increased and lysine levels decreased markedly in rats fed the alkyl caseins. The respective alkyllsine derivatives were present in plasma and urine. In another experiment, nearly normal or normal growth was obtained by feeding lysine-supplemented methyl or isopropyl casein, respectively. A preparation of partially methylated casein, containing approximately equal amounts of monomethyl- and dimethyllysines, supported normal rat growth. These results demonstrate that lysine deficiency was produced by feeding highly alkylated caseins. Digestibility of the chemically modified caseins in vivo was not affected, although in vitro studies with trypsin and alpha-chymotrypsin showed lowered digestibility. Since no apparent toxicity was observed limited methylation of food proteins may...Continue Reading


Aug 23, 2006·Journal of Biomedical Materials Research. Part B, Applied Biomaterials·Paul F GratzerJ Michael Lee
Mar 1, 1981·International Journal of Peptide and Protein Research·K F GeogheganR E Feeney
Jan 1, 1979·International Journal of Peptide and Protein Research·K FretheimR E Feeney

Related Concepts

Casein A
Food Preservation
Lysine Hydrochloride

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