Semisynthetic Analogues of an Enzymically Active Complex Formed between Two Overlapping Fragments of Staphylococcal Nuclease

Abstract

Abstract It has been shown previously that a cyanogen bromide fragment of staphylococcal nuclease (149 residues) containing the COOH-terminal portion of the molecule (residues 99 to 149) can undergo noncovalent interaction with a product of limited trypsin digestion of nuclease (residues 1 to 126) to yield a complex with approximately 10% the enzymic activity of the native protein. The two interacting fragments, when alone in solution, appear to be essentially structureless while the active complex exhibits much of the ordered structure of nuclease itself. The studies reported here have investigated, in a qualitative manner, the minimum structural requirements of the (99-149) fragment for productive complementation. The single tryptophan residue of nuclease, at position 140, may be replaced with phenylalanine and the fragment may be shortened at the NH2 terminus to the region of residues 116 to 117 and at the COOH terminus to position 140 without elimination of capacity to support the formation of a complex with at least partial activity.

Keywords

Affiliated Institutions

• National Institute of Arthritis and Musculoskeletal and Skin Diseases US
• National Institutes of Health US

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