Utilization of dipeptides by the caprine mammary gland for milk protein synthesis

F R Backwell, B J Bequette, Dana Lorraine Wilson, Alexander Graham Calder, J A Metcalf, D Wray-Cahen, C MacRae, D E Beever, Gerald Lobley

Research output: Contribution to journalArticle

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Abstract

Specific use by the mammary gland in vivo of amino acids (AA) of peptide origin has been demonstrated in lactating dairy goats using a dual-labeled tracer technique involving close-arterial (external pudic artery, EPA) infusion of 13C-labeled dipeptides. The extent of utilization does not appear to differ for glycyl-L-[1-13C]phenylalanine and glycyl-L-[1-13C]leucine, perhaps indicative of a common mechanism by which AA are incorporated from peptide into milk protein. [1-13C]phenyl-alanine of peptide origin appears to be concentrated within the red blood cell, suggesting a role for the erythrocyte in peptide metabolism in vivo. In conclusion, it appears that the lactating mammary gland of goats has the ability to utilize AA of peptide origin for milk protein synthesis, and while the mechanism by which [1-13C]AA are incorporated into milk protein is not clear, it may involve peptide hydrolysis by either mammary cell surface or red blood cell hydrolases followed by uptake of liberated AA by the mammary gland.
Original languageEnglish
Pages (from-to)R1-6
JournalAmerican Journal of Physiology
Volume267
Issue number1 Pt 2
Publication statusPublished - 1 Jul 1994

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Dipeptides
Milk Proteins
Human Milk
Human Mammary Glands
Peptides
Amino Acids
Erythrocytes
Goats
glycylphenylalanine
Hydrolases
Leucine
Alanine
Breast
Hydrolysis
Arteries

Keywords

  • Amino Acids
  • Animals
  • Caseins
  • Dipeptides
  • Female
  • Goats
  • Lactation
  • Leucine
  • Mammary Glands, Animal
  • Milk Proteins
  • Peptides
  • Phenylalanine

Cite this

Backwell, F. R., Bequette, B. J., Wilson, D. L., Calder, A. G., Metcalf, J. A., Wray-Cahen, D., ... Lobley, G. (1994). Utilization of dipeptides by the caprine mammary gland for milk protein synthesis. American Journal of Physiology, 267(1 Pt 2), R1-6.

Utilization of dipeptides by the caprine mammary gland for milk protein synthesis. / Backwell, F R; Bequette, B J; Wilson, Dana Lorraine; Calder, Alexander Graham; Metcalf, J A; Wray-Cahen, D; MacRae, C; Beever, D E; Lobley, Gerald.

In: American Journal of Physiology, Vol. 267, No. 1 Pt 2, 01.07.1994, p. R1-6.

Research output: Contribution to journalArticle

Backwell, FR, Bequette, BJ, Wilson, DL, Calder, AG, Metcalf, JA, Wray-Cahen, D, MacRae, C, Beever, DE & Lobley, G 1994, 'Utilization of dipeptides by the caprine mammary gland for milk protein synthesis', American Journal of Physiology, vol. 267, no. 1 Pt 2, pp. R1-6.
Backwell FR, Bequette BJ, Wilson DL, Calder AG, Metcalf JA, Wray-Cahen D et al. Utilization of dipeptides by the caprine mammary gland for milk protein synthesis. American Journal of Physiology. 1994 Jul 1;267(1 Pt 2):R1-6.
Backwell, F R ; Bequette, B J ; Wilson, Dana Lorraine ; Calder, Alexander Graham ; Metcalf, J A ; Wray-Cahen, D ; MacRae, C ; Beever, D E ; Lobley, Gerald. / Utilization of dipeptides by the caprine mammary gland for milk protein synthesis. In: American Journal of Physiology. 1994 ; Vol. 267, No. 1 Pt 2. pp. R1-6.
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AB - Specific use by the mammary gland in vivo of amino acids (AA) of peptide origin has been demonstrated in lactating dairy goats using a dual-labeled tracer technique involving close-arterial (external pudic artery, EPA) infusion of 13C-labeled dipeptides. The extent of utilization does not appear to differ for glycyl-L-[1-13C]phenylalanine and glycyl-L-[1-13C]leucine, perhaps indicative of a common mechanism by which AA are incorporated from peptide into milk protein. [1-13C]phenyl-alanine of peptide origin appears to be concentrated within the red blood cell, suggesting a role for the erythrocyte in peptide metabolism in vivo. In conclusion, it appears that the lactating mammary gland of goats has the ability to utilize AA of peptide origin for milk protein synthesis, and while the mechanism by which [1-13C]AA are incorporated into milk protein is not clear, it may involve peptide hydrolysis by either mammary cell surface or red blood cell hydrolases followed by uptake of liberated AA by the mammary gland.

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