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Amino Acid Utilization by L-M Strain Mouse Cells in a Chemically Defined Medium

Gary D. Stoner and Donald J. Merchant
In Vitro
Vol. 7, No. 5 (Mar. - Apr., 1972), pp. 330-343
Stable URL: http://www.jstor.org/stable/4291619
Page Count: 14
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Amino Acid Utilization by L-M Strain Mouse Cells in a Chemically Defined Medium
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Abstract

The amino acid requirements of strain L-M mouse cells grown in a chemically defined medium (2X Eagle) containing only the 13 essential amino acids (EAA) were investigated. Medium and acid hydrolysate samples were analyzed for amino acid content by the method of ion exchange chromatography. The extent of utilization of the EAA differed; e.g. after 120 hr of cell growth without medium change, glutamine was exhausted from the medium; methionine, leucine, isoleucine, cystine, arginine, and valine were depleted 60 to 80%; other EAA were used to lesser extents. Although the EAA were used in excess of their requirements for protein synthesis, a correlation could generally be made between utilization and protein amino acid composition. Glutamine appeared to be a growth-limiting factor. Use of $U-^{14}C-labeled$ glutamine indicated that over one-half of the metabolized glutamine was converted to carbon dioxide, 17% to cell material, and 15% was extracted from the amino acid pools. Nonessential amino acids (NEAA), viz. alanine, aspartic acid, glutamic acid, glycine, proline, and serine, were released into the medium during growth, and some were re-utilized. Exogenous provision of these did not improve cell growth. In contrast to the other NEAA, only serine showed net utilization when provided exogenously. When glutamic acid largely replaced the glutamine in the medium, it exerted a sparing effect on the glutamine requirement for protein synthesis. Suggestions are given for the improvement of Eagle medium for cell growth.

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