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From Proteopedia

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Semisynthetic Ribonuclease A

Introduction

The synthesis of a fully active semisynthetic RNase A supports the hypothesis that the amino acid sequence of a protein solely dictates the formation of an active enzyme and demonstrates that an enzyme with the catalytic activity and specificity of a naturally produced enzyme can be made in laboratory. Semisynthetic RNase A illustrates that functional enzymes can be produced from merely the individual constituent amino acid residues. Polypeptide synthesis can provide new routes to the study of enzymes through the selective modification of natural proteins to assay individual roles of amino acids in folding and catalysis.

Function

The structure to function relationship is clearly exhibited by semisynthetic RNase A. In the RNase A protein, the removal of six C terminal residues, leaving RNase 1-118, completely halts enzymatic activity (Martin, 1987). However, a complex of RNase 1-118 with a synthetic polypeptide comprising the C terminal residues 111-124 restores enzymatic activity to RNase A. Upon the addition of the synthetic chain, the semisynthetic enzyme adopts a structure that closely resembles that of natural RNase (Martin, 1987). The restoration of the structure reconstitutes the enzymatic activity of RNase to 98% (Martin, 1987).

References

Martin, Philip D., Marilynn S. Doscher, and Brian F. P. Edwards. "The Redefined Crystal Structure of a Fully Active Semisynthetic Ribonuclease at 1.8-A Resolution." The Journal of Biological Chemistry 262.33 (1987): 15930-5938.