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Accommodation of single amino acid insertions by the native state of staphylococcal nuclease
Author(s) -
Sondek John,
Shortle David
Publication year - 1990
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340070402
Subject(s) - alanine , chemistry , nuclease , guanidine , amino acid , circular dichroism , residue (chemistry) , stereochemistry , denaturation (fissile materials) , native state , active site , protein secondary structure , glycine , protein engineering , protein structure , protein folding , biochemistry , crystallography , dna , enzyme , nuclear chemistry
Single alanine and glycine insertions were introduced at 20 randomly selected positions in staphylococcal nuclease. The resulting changes in catalytic activity and in stability to guanidine hydrochloride denaturation indicate that the native state structure is frequently able to accommodate the extra residue without great difficulty, even insertions within secondary structural elements such as alpha helices and beta sheets. On average, an inserted residue reduces the free energy of denaturation (ΔG H 2 O ) by an amount roughly comparable to an alanine or glycine substitution for one of the residues flanking the site of insertion. Several positions outside of the enzyme active site were found where insertions, but not substitutions, lead to structural changes that modify catalytic activity and the circular dichroism spectrum. Amino acid insertions represent a virtually unexplored class of genetic mutation that may prove complementary to amino acid substitutions for engineering proteins with altered functional and structural properties.