Aspartic acid configuration change

It was first observed by Walden, in 1896, that a change of configuration took place in the conversion of the malic acids into the chlorosuc-cinic acids and vice versd. His results were collected together in 1897 and expressed in the following scheme, in which was included Tilden and Marshall s observations on aspartic acid —... 

Enzymes can be either totally specific for a given substrate, to such an extent that they will not tolerate any structural or configurational changes in the substrate, or they can be broadly specific for a given type of functional group, and they will still operate on substrates with structural variations around that functional group. An example of the former is the enzyme aspartase, Asp, which catalyzes both the addition of ammonia to fumaric acid and the elimination of ammonia from L-aspartic acid by the following reactions ... 

The interaction of aspartic acid and other ligands with complexes of Tb " with edta and related ligands has also been studied and association constants determined. The complex formation between Tb " or Eu " and (r)-( — )-l,2-propanediaminetetraacetic add or (r,r)-trons-1,2-cyclohexanediaminetetraacetic acid has been similarly investigated. The pH dependence of the circularly polarized and total luminescence shows a drastic configurational change of the chelate system at pH 10.5-11, corresponding, it is believed, to formation of hydroxide complexes. Tlie technique of magnetic-field-induced circularly polarized emission has been introduced for lanthanide ions the mechanisms of lanthanide transition intensities are also discussed in the paper. 

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