Table 1.

Time Constants of Molecular Dynamics, Protein Motion and Catalysis^a

Time		sec
	s	1			common kcat range
	ms	10−1
		10−2		kcat PNP
		10−3	flap opening TIM	kchem PNP
	μs	10−4	rate O2 Hb to deoxy Hb	loop motion PNP
		10−5	flap closing OPRTase and PTPase		domain motion in protein
		10−6
	ns	10−7		substrate/ligand binding PNPb
		10−8			rotation/translation for NACs catalytic site capture limita
		10−9
	ps	10−10	H2O diffuses two diameters
		10−11	collisionless H+ ion transfer
		10−12	light travels 0.3 mm
	fs	10−13	bond vibration; TS lifetime
		10−14		TS PNPc
		10−15

^aModified from ref (18).

^bFrom ref (38).

^cFrom ref (17).