Analysis of the interaction between charged side chains and the .alpha.-helix dipole using designed thermostable mutants of phage T4 lysozyme

Biochemistry ◽  
1991 ◽  
Vol 30 (41) ◽  
pp. 9816-9828 ◽  
Author(s):  
H. Nicholson ◽  
D. E. Anderson ◽  
S. Dao Pin ◽  
B. W. Matthews
Keyword(s):  
Alpha Helix ◽  
Side Chains ◽  
T4 Lysozyme ◽  
Phage T4

Replacements of Pro86 in phage T4 lysozyme extend an alpha-helix but do not alter protein stability

Science ◽  
1988 ◽  
Vol 239 (4840) ◽  
pp. 631-635 ◽  
Author(s):  
T Alber ◽  
J. Bell ◽  
D. Sun ◽  
H Nicholson ◽  
J. Wozniak ◽  
...  
Keyword(s):  
Protein Stability ◽  
Alpha Helix ◽  
T4 Lysozyme ◽  
Phage T4

scholarly journals Stabilization of phage T4 lysozyme by engineered disulfide bonds

1989 ◽  
Vol 86 (17) ◽  
pp. 6562-6566 ◽  
Author(s):  
M Matsumura ◽  
W J Becktel ◽  
M Levitt ◽  
B W Matthews
Keyword(s):  
Disulfide Bonds ◽  
Theoretical Calculations ◽  
Equilibrium Constants ◽  
T4 Lysozyme ◽  
Disulfide Bridges ◽  
Large Loop ◽  
Phage T4 ◽  
Flexible Part ◽  
Free Phage

Four different disulfide bridges (linking positions 9-164, 21-142, 90-122, and 127-154) were introduced into a cysteine-free phage T4 lysozyme at sites suggested by theoretical calculations and computer modeling. The new cysteines spontaneously formed disulfide bonds on exposure to air in vitro. In all cases the oxidized (crosslinked) lysozyme was more stable than the corresponding reduced (noncrosslinked) enzyme toward thermal denaturation. Relative to wild-type lysozyme, the melting temperatures of the 9-164 and 21-142 disulfide mutants were increased by 6.4 degrees C and 11.0 degrees C, whereas the other two mutants were either less stable or equally stable. Measurement of the equilibrium constants for the reduction of the engineered disulfide bonds by dithiothreitol indicates that the less thermostable mutants tend to have a less favorable crosslink in the native structure. The two disulfide bridges that are most effective in increasing the stability of T4 lysozyme have, in common, a large loop size and a location that includes a flexible part of the molecule. The results suggest that stabilization due to the effect of the crosslink on the entropy of the unfolded polypeptide is offset by the strain energy associated with formation of the disulfide bond in the folded protein. The design of disulfide bridges is discussed in terms of protein flexibility.

Das sterische Verhalten der Alpha-Helix / The steric Behaviour of the Alpha-Helix

1969 ◽  
Vol 24 (6) ◽  
pp. 672-690 ◽  
Author(s):  
R. Jarosch
Keyword(s):  
Hydrogen Bonds ◽  
Polypeptide Chain ◽  
Enzymatic Catalysis ◽  
Alpha Helix ◽  
Side Chains ◽  
Tertiary Structures ◽  
General Variation ◽  
Coiling Direction ◽  
Α Helix ◽  
Molecule Model

The steric behaviour of the α-Helix has been investigated using an elastic molecule-model made of solid rubber balls and steel pins. Shortening of the hydrogen-bonds, which is possible at least in the range from 2.91 to 2.67 A in real α-Helices, has the following effects:1. The α-Helix contracts proportionally to the length of the hydrogen-bonds (figs. 3, 4).2. A torsional force arises leading in the case of longer α-Helices to torsional revolutions of the free ends of the helix (figs. 3 a. 4 a).3. Tertiary structures (superhelices. flattened superhelices. planar wavy lines, planar arcs) superpose the α-Helix if only specific hydrogen-bonds (e. g. indicated by arrows in fig. 5) will be shortened and if the distance between them is repeated in the sequence of the polypeptide chain (Tab. I). Some of the sequence-distances show similar tertiary structures and the same pitches of the superhelices (Tab. II). A general variation in the length of the hydrogen-bonds causes alterations in the superstructure and can also change the coiling direction of the superhelix.4. The Cα— Cβ; bonds incline slightly to the axis of the helix (fig. 11) through which the α-Helix with side chains becomes a little thinner. Because of the torsion (see item 2) the distance between the side chains changes also (fig. 12). The distances increase between specific positions of the side chains and decrease between others (Tab. III).Possible reasons for the shortening of the hydrogen-bonds are briefly discussed. The importance of the described behaviour for biological movements, enzymatic catalysis (“allosteric effect”) and active transport is emphasized.

Toward a simplification of the protein folding problem: a stabilizing polyalanine .alpha.-helix engineered in T4 lysozyme

Biochemistry ◽  
1991 ◽  
Vol 30 (8) ◽  
pp. 2012-2017 ◽  
Author(s):  
X. J. Zhang ◽  
W. A. Baase ◽  
B. W. Matthews
Keyword(s):  
Protein Folding ◽  
Alpha Helix ◽  
T4 Lysozyme

A differential scanning calorimetric study of the thermal unfolding of seven mutant forms of phage T4 lysozyme

Biochemistry ◽  
1991 ◽  
Vol 30 (7) ◽  
pp. 1887-1891 ◽  
Author(s):  
Patrick Connelly ◽  
Lily Ghosaini ◽  
Cui-Qing Hu ◽  
Shinichi Kitamura ◽  
Akiyoshi Tanaka ◽  
...  
Keyword(s):  
Thermal Unfolding ◽  
Differential Scanning Calorimetric ◽  
Calorimetric Study ◽  
T4 Lysozyme ◽  
Phage T4 ◽  
Mutant Forms
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