Chemical and mouse growth tests for nutritional assessment of commercial lactoferrins

• Published in: Nutrition research (New York, N.Y.) Vol. 13; no. 9; pp. 1087 - 1097
• Main Authors: Ujiie, M., Sarwar, G., Peace, R.W., Watson, D.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.09.1993; Elsevier Science
• Subjects: Amino acid sequence; Bioavailability; Biological and medical sciences; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Human/bovine milk; Lactoferrin; Lysine; Mouse; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Amino acid sequence; Lactoferrin; Human/bovine milk; Bioavailability; Mouse; Lysine; Ferroprotein; Nutrition; Nutritive value; Rodentia; Standardization; Vertebrata; Mammalia; Commercial form; Measurement method; Whey protein; Aminoacid sequence
• ISSN: 0271-5317; 1879-0739
• DOI: 10.1016/S0271-5317(05)80527-5

Some electrophoretic analysis, N-terminal amino acid sequencing, and a mouse growth test were developed and/or standardized for chemical and nutritional assessment of lactoferrins. Commercial samples of human milk, bovine milk and bovine colostrum lactoferrins, and an isolated sample of human milk lactoferrin were studied. Bovine milk and colostrum lactoferrin were identical in N-terminal amino acid sequence. Human milk lactoferrin (commercial), however, showed three N-terminal amino acid sequences, while the isolated human milk lactoferrin displayed a single N-terminal amino acid sequence. Human and bovine lactoferrin had 48% homology (14/29 residues) in the N-terminal amino acid sequence. The isoelectric points of the four lactoferrins were determined with a rapid automated electrophoretic system, and all four proteins showed numerous bands on the gel. A mouse growth study was conducted to determine bioavailability of lysine in commercial samples of human milk and bovine milk lactoferrins. A wheat gluten (20%) basal diet adequate in all nutrients except lysine (0.26%) was supplemented with graded levels of crystalline lysine (0.1 to 0.7%) or lactoferrin each providing 0.1% lysine. Lysine bioavailability was calculated by comparing growth of mice fed the lactoferrin diets with those fed basal plus 0.1% crystalline lysine. Values for bioavailability of lysine in human and bovine lactoferrins were 89 and 94%, respectively; suggesting nutritional availability of these lacto proteins.