Kinetic characterisation of arylamine N-acetyltransferase from Pseudomonas aeruginosa

BMC Biochemistry

Table 1 Definitions of parameters in the normalised velocity equation (eq 3)^a

Parameter^b	Definition^c	Comments
α	K _iB K _mA	Appears in Ordered Bi Bi only
β	$\frac{K_{mA} b^{2} B^{2}}{K_{si (B \to E)}}$	Accounts for substrate inhibition by 5-aminosalicylic acid on the free enzyme
γ	$\frac{a A b^{2} B^{2}}{K_{si (B \to_{FP}^{EA})}}$	Accounts for substrate inhibition by 5-aminosalicylic acid on the enzyme·AcCoA complex
den	$α + K_{mB} A + K_{mA} B + A B + \frac{β}{b^{2}} + \frac{γ}{a b^{2}}$	The denominator term den is independent of both a and b

^aThe parameters α, β and γ are set to zero in different combinations to define different mechanisms.
^bThe definition of γ given here is for the Ping Pong Bi Bi mechanism (in which α = 0). γ for the Ordered Bi Bi mechanism is similar, however the denominator would be $K_{si (B \to_{EPQ}^{EAB})}$ , relating to the binding of 5-aminosalicylic acid to either of the trimolecular EAB or EPQ complexes.
^cThe K_i and K_si terms are true dissociation constants for the enzyme·substrate complexes indicated, and K_m values are Michaelis constants for the substrates indicated.

ISSN: 1471-2091