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Single‐point amino acid substitutions at the 119th residue of thermolysin and their pressure‐induced activation
Author(s) -
Kunugi Shigeru,
Fujiwara Satoshi,
Kidokoro Shun-ichi,
Endo Kimiko,
Hanzawa Satoshi
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01485-4
Subject(s) - thermolysin , chemistry , mutant , enzyme , residue (chemistry) , atmospheric pressure , amino acid , amino acid residue , wild type , stereochemistry , biophysics , biochemistry , peptide sequence , biology , gene , geology , oceanography , trypsin
The effect of amino acid substitution at the 119th site of thermolysin (TLN) on the pressure activation behavior of this enzyme was studied for four mutants at pressures <300 MPa. For Q119Q, Q119N and Q119R, the highest activation was observed to be over 30 times that at atmospheric pressure and the activation volumes (Δ V ‡ ) were about −75 ml/mol. However, we obtained only 10 times higher activation for Q119E and Q119D (Δ V ‡ ∼−60 ml/mol). The intrinsic fluorescence of TLN changed at pressures >300 MPa, and the latter two mutants showed a smaller Δ G app and Δ V app of transition than the wild type. These results are discussed with respect to the hydration change in the enzyme protein around the substituted region.