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Journal of Biosciences

, Volume 34, Issue 6, pp 853–872 | Cite as

A weak link in metabolism: the metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesis

  • Enrique Meléndez-Hevia
  • Patricia de Paz-Lugo
  • Athel Cornish-Bowden
  • María Luz Cárdenas
Article

Abstract

In a previous paper, we pointed out that the capability to synthesize glycine from serine is constrained by the stoichiometry of the glycine hydroxymethyltransferase reaction, which limits the amount of glycine produced to be no more than equimolar with the amount of C 1 units produced. This constraint predicts a shortage of available glycine if there are no adequate compensating processes. Here, we test this prediction by comparing all reported fluxes for the production and consumption of glycine in a human adult. Detailed assessment of all possible sources of glycine shows that synthesis from serine accounts for more than 85% of the total, and that the amount of glycine available from synthesis, about 3 g/day, together with that available from the diet, in the range 1.5–3.0 g/day, may fall significantly short of the amount needed for all metabolic uses, including collagen synthesis by about 10 g per day for a 70 kg human. This result supports earlier suggestions in the literature that glycine is a semi-essential amino acid and that it should be taken as a nutritional supplement to guarantee a healthy metabolism.

Keywords

Collagen collagen synthesis collagen turnover essential amino acid glycine glycine metabolism osteoarthritis osteoporosis 

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Copyright information

© Indian Academy of Sciences 2009

Authors and Affiliations

  • Enrique Meléndez-Hevia
    • 1
  • Patricia de Paz-Lugo
    • 1
  • Athel Cornish-Bowden
    • 2
  • María Luz Cárdenas
    • 2
  1. 1.Departamento de Investigación CientíficaInstituto del Metabolismo CelularTenerife, Canary IslandsSpain
  2. 2.Unité de Bioénergétique et Ingénierie des ProtéinesCentre National de la Recherche ScientifiqueMarseille Cedex 20France

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