Pseudo First-Order Kinetics and HX Rate Constants

2 Pseudo First-Order Kinetics and HX Rate Constants 

In most cases of protein HX studies, the exchange reaction is the rate-limiting step (called the EX2 mechanism as will be discussed later, see also Sections 1.3 and 3.2.2). Because the solvent deuterium concentration in an HX experiment is usually in large excess and remains approximately constant, the exchange reaction of each exchangeable hydrogen is a pseudo first-order reaction and follows 

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