Stabilization of a protein by removal of unfavorable abnormal pKa: substitution of undissociable residue for glutamic acid-35 in chicken lysozyme.


Glu35 in chicken lysozyme has an abnormally high pKa (6.1) partly due to the hydrophobic environment provided by Trp108. The relationship between protein stability and abnormal pKa was investigated in detail by using mutant lysozymes in which Glu35 was replaced by undissociable residues and an oppositely ionizable residue. It was found that lysozyme was stabilized at alkaline pH range by the replacement of Glu35 with an undissociable residue, Gln (E35Q lysozyme) or Al (E35A lysozyme). On the other hand, when Glu35 was replaced by His (E35H lysozyme), which could have an opposite charge to Glu by ionization, the introduced His35 was found to have an abnormally low pKa (3.6), leading to the destabilization of lysozyme at acidic pH. These observations are completely consistent with the situation that the environment around Glu35 is highly hydrophobic and therefore the placement of either a positive or negative charge in such an environment leads to destabilization of lysozyme. These observations also indicate that the replacement of an acidic residue having abnormally high pKa or a basic residue having abnormally low pKa by an undissociable residue is a very efficient and general method for stabilization of a protein. Study holds ProTherm entries: 1749, 1750, 1751, 1752, 1753, 1754, 1755, 1756, 1757, 1758, 1759, 1760, 1761, 1762, 1763, 1764, 1765, 1766, 1767, 1768 Extra Details: chicken lysozyme; glutamic acid; protein stability;,hydrophobic; stabilization

Submission Details

ID: 3DfW5ByY3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:17 p.m.

Version: 1

Publication Details
Inoue M;Yamada H;Hashimoto Y;Yasukochi T;Hamaguchi K;Miki T;Horiuchi T;Imoto T,Biochemistry (1992) Stabilization of a protein by removal of unfavorable abnormal pKa: substitution of undissociable residue for glutamic acid-35 in chicken lysozyme. PMID:1390669
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Lysozyme C P00698 LYSC_CHICK
96.9 Lysozyme C P00700 LYSC_COLVI
96.9 Lysozyme C P00699 LYSC_CALCC
96.9 Lysozyme C Q7LZQ0 LYSC_CATWA
96.9 Lysozyme C Q7LZP9 LYSC_LOPIM
96.1 Lysozyme C Q7LZI3 LYSC_TRASA
95.3 Lysozyme C P00701 LYSC_COTJA
96.1 Lysozyme C P19849 LYSC_PAVCR
95.3 Lysozyme C P22910 LYSC_CHRAM
95.3 Lysozyme C Q7LZT2 LYSC_TRATE
95.2 Lysozyme C P00703 LYSC_MELGA
92.2 Lysozyme C P00704 LYSC_NUMME
93.0 Lysozyme C P24364 LYSC_LOPLE
94.6 Lysozyme C P24533 LYSC_SYRRE
93.2 Lysozyme C P00702 LYSC_PHACO
93.0 Lysozyme C P81711 LYSC_SYRSO
92.3 Lysozyme C P49663 LYSC_PHAVE
99.2 Lysozyme C P79179 LYSC_GORGO
99.2 Lysozyme C P61626 LYSC_HUMAN
99.2 Lysozyme C P61627 LYSC_PANPA
99.2 Lysozyme C P61628 LYSC_PANTR
98.5 Lysozyme C P79239 LYSC_PONPY
96.2 Lysozyme C P79180 LYSC_HYLLA