scholarly journals Conformational Change in the Catalytic Site of the Ribonuclease YoeB Toxin by YefM Antitoxin

2005 ◽  
Vol 19 (4) ◽  
pp. 497-509 ◽  
Author(s):  
Katsuhiko Kamada ◽  
Fumio Hanaoka
Keyword(s):  
Conformational Change ◽  
Catalytic Site

scholarly journals Activation of the first component of human complement (C1) by antibody—antigen aggregates

1978 ◽  
Vol 175 (2) ◽  
pp. 383-390 ◽  
Author(s):  
A W Dodds ◽  
R B Sim ◽  
R R Porter ◽  
M A Kerr
Keyword(s):  
Conformational Change ◽  
Proteolytic Activity ◽  
Maximum Rate ◽  
Catalytic Site ◽  
The Other ◽  
Peptide Chain ◽  
Human Complement ◽  
Rate Of Activation

The activation of subcomponents C1r and C1s in the first component of complement, C1, when bound to antibody-antigen complexes was investigated. Activation was followed both by the splitting of the peptide chains of subcomponents C1r and C1s and by the development of proteolytic activity. For the maximum rate of activation to occur, all components must be present in approximate molar proportions of antibody: C1q:C1r:C1s of 13:1:5:5. For activation of subcomponent C1s, subcomponents C1r or C1r, but not C1r inactivated with iPr2P-F (di-isopropyl phosphorofluorideate), are effective. For activation of subcomponent C1r, subcomponents C1s, C1s or C1s inactivated with iPr2P-F are effective. Subcomponent C1s is activated by C1r, and C1r is activated autocatalytically, probably through the formation of an intermediary C1r. in which the peptide chain is unsplit but a conformational change caused by interaction with the other components has led to the formation of a catalytic site able to split subcomponent C1r to C1r.

scholarly journals Temperature-dependences of the kinetics of reactions of papain and actinidin with a series of reactivity probes differing in key molecular recognition features

2006 ◽  
Vol 396 (1) ◽  
pp. 17-21 ◽  
Author(s):  
Sheraz Gul ◽  
Geoffrey W. Mellor ◽  
Emrys W. Thomas ◽  
Keith Brocklehurst
Keyword(s):  
Conformational Change ◽  
Rate Constants ◽  
Catalytic Site ◽  
Stopped Flow ◽  
Thiol Groups ◽  
Cysteine Peptidases ◽  
Temperature Dependences ◽  
Significant Conformational Change ◽  
Kinetics Of ◽  
Molecular Recognition Features

The temperature-dependences of the second-order rate constants (k) of the reactions of the catalytic site thiol groups of two cysteine peptidases papain (EC 3.4.22.2) and actinidin (EC 3.4.22.14) with a series of seven 2-pyridyl disulphide reactivity probes (R-S-S-2-Py, in which R provides variation in recognition features) were determined at pH 6.7 at temperatures in the range 4–30 °C by stopped-flow methodology and were used to calculate values of ΔS‡, ΔH‡ and ΔG‡. The marked changes in ΔS‡ from negative to positive in the papain reactions consequent on provision of increase in the opportunities for key non-covalent recognition interactions may implicate microsite desolvation in binding site–catalytic site signalling to provide a catalytically relevant transition state. The substantially different behaviour of actinidin including apparent masking of changes in ΔH‡ by an endothermic conformational change suggests a difference in mechanism involving kinetically significant conformational change.

scholarly journals Ligand-specific conformational change drives interdomain allostery in Pin1

2021 ◽  
Author(s):  
Beat Vogeli ◽  
Alexandra Born ◽  
Janne Soetbeer ◽  
Morkos Henen ◽  
Frauke Breitgoff ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Ligand Binding ◽  
Conformational Change ◽  
Conformational Changes ◽  
Catalytic Domain ◽  
Catalytic Site ◽  
The Other ◽  
Allosteric Mechanism ◽  
Catalytic Loop ◽  
Extended States

Abstract Pin1 is a two-domain cell regulator that isomerizes peptidyl-prolines. The catalytic domain (PPIase) and the other ligand-binding domain (WW) sample extended and compact conformations. Ligand binding changes the equilibrium of the interdomain conformations, but the conformational changes that lead to the altered domain sampling were unknown. Prior evidence has supported an interdomain allosteric mechanism. We recently introduced a magnetic resonance-based protocol that allowed us to determine the coupling of intra- and interdomain structural sampling in apo Pin1. Here, we describe ligand-specific conformational changes that occur upon binding of pCDC25c and FFpSPR. pCDC25c binding doubles the population of the extended states compared to the virtually identical populations of the apo and FFpSPR-bound forms. pCDC25c binding to the WW domain triggers conformational changes to propagate via the interdomain interface to the catalytic site, while FFpSPR binding displaces a helix in the PPIase that leads to repositioning of the PPIase catalytic loop.

Dual-Function, Light Switchable Cobalt Catalysis via Active Site Metamorphosis

2019 ◽  
Author(s):  
Enrico Bergamaschi ◽  
Frédéric Beltran ◽  
Christopher Teskey
Keyword(s):  
Visible Light ◽  
Active Site ◽  
Catalytic Site ◽  
Dual Function ◽  
Catalytic Systems ◽  
Hydride Complex ◽  
Dual Functional ◽  
Multiple Processes ◽  
Olefin Migration

<p></p><p></p><p>Switchable catalysis offers opportunities to control the rate or selectivity of a reaction <i>via</i> a stimulus such as pH or light. However, few examples of switchable catalytic systems that can facilitate multiple processes exist. Here we report a rare example of such dual-functional, switchable catalysis. Featuring an easily prepared, bench-stable cobalt(I) hydride complex in conjunction with pinacolborane, we can completely alter the reaction outcome between two widely employed transformations – olefin migration and hydroboration – with visible light as the sole trigger. This dichotomy arises from ligand photodissociation which leads to metamorphosis of the active catalytic site, resulting in divergent mechanistic pathways.</p><p></p><p></p>

Sign in / Sign up

Export Citation Format

Share Document