Coupling enzyme catalysis

The real-time single-turnover trajectories also enabled Xie and coworkers to analyze the time-dependent activity of each enzyme molecule. They found that individual COx molecules show temporal activity fluctuations (i.e., dynamic disorder in activity), attributable to the slow conformational dynamics of the enzyme. The timescale of the activity fluctuation is the timescale of the conformational dynamics that are longer than the catalytic turnovers and can be obtained from the autocorrelation function of the waiting times (Figure 1(d)), which shows an exponential decay behavior versus the index of turnovers (m) and whose decay constant is the fluctuation timescale. This conformational dynamics-coupled enzyme catalysis is fundamental to enzyme catalysis and extremely challenging to study with traditional methods measuring the average behaviors of a population of molecules. 

Most catalytic cycles are characterized by the fact that, prior to the rate-determining step [18], intermediates are coupled by equilibria in the catalytic cycle. For that reason Michaelis-Menten kinetics, which originally were published in the field of enzyme catalysis at the start of the last century, are of fundamental importance for homogeneous catalysis. As shown in the reaction sequence of Scheme 10.1, the active catalyst first reacts with the substrate in a pre-equilibrium to give the catalyst-substrate complex [20]. In the rate-determining step, this complex finally reacts to form the product, releasing the catalyst... 

Sutcliffe, M.J. and Scrutton, N.S. (2002). A new conceptual framework for enzyme catalysis. Hydrogen tunnelling coupled to enzyme dynamics in flavoprotein and quinoprotein enzymes. Eur. J. Biochem. 269, 3096-3102... 

In enzyme catalysis, 249, 373-397 [bovine serum amine oxidase, 249, 393-394 coupled motion and, 249, 386-388 demonstration, 249, 374-386 (breakdown of rule of geometric mean in,... 

Asymmetric Transformations by Coupled Enzyme and Metal Catalysis Dynamic Kinetic Resolution... 

A step-by-step peptide synthesis from the N- to the C-terminus is not possible with chemical methods as it risks partial epimerization due to the repeated carboxy activation procedures, In constrast, the stereo- and regiospecificity of serine and cysteine proteases ensures integrity of the stereogenic center and allows ecological reaction conditions without side-chain protection. Scheme 4 shows the synthesis scheme using clostripain and chymo-trypsin as catalysts.The second coupling reaction was carried out by enzyme catalysis in a frozen aqueous system (see Section 4.2.3.1). 

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