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2) Nonstandard AAs

Many of the nonstandard amino acids in nature metabolically derive from the standard AAs as illustrated by the two examples in the diagram below.

T#5: Metabolic synthesis of MET from ASP by NONSTANDARD AA intermediates

Aspartic, Asp, D -aspartyl phosphateaspartate semialdehyde

homoserinehomocysteinemethionine, Met, M

The diagram above shows the metabolic pathways in bacteria for the synthesis of Met beginning with Asp. The intermediate steps in these pathways include several nonstandard AAs. The complete pathway is illustrate in Fig. 24-45 in your text as you'll learn more about next quarter.

T#6: Figure 24-45. Biosynthesis of " Asp family" amino acids