Rational polynomial representation of ribonucleotide reductase activity

BMC Biochemistry

Table 1 Parameter estimates of the reductase models. Fits to data are as shown in Figure 2.

substrate	K_sdATP	K_sATP	K_sdTTP	K_sdGTP	K_idATP	K_iATP	K_aATP	k₂	k_2dA	k_2A	k_2e	k₄	k₆
ADP	2	200	2.4^b	0.5	1.25	300	2000^d	0.21				0.03	0.16
GDP	1	100	0.5	2	2	190	2400	0.28^a				0.04	0.19
CDP	2	70	1.55^b	2^c	1.5	600	1400		0.25^a	0.29^a	0.08		0.32
UDP	1	100	0.7^b	2^c	0.5	200	800		0.26	0.26			0.26^a

Binding constants in μM, rate constants in 1/s.
^afixed values taken directly from table 5 of [5].
^busing Eq. 10, these were adjusted to yield fluxes of 12.5, 12.5, 20 and 5 (uM/min) for ADP, GDP, CDP and UDP, respectively, under assumptions of E₀ = 16 μM, ADP = 430 μM, GDP = 110 μM, CDP = 55 μM, UDP = 170 μM, K_mADP = 12 μM, K_mGDP = 4.9 μM, K_mCDP = 2 μM, K_mUDP = 6.4 μM, ATP = 1450 μM, dATP = 10.5 μM, dGTP = 7.3 μM, dTTP = 30 μM and the remaining parameter values in Table 1, see [7].
^cno data, thus, these can be assumed to have any value between .5 and 2; a default value of 2 was carried down from GDP.
^dno data, 2000 is based on the other rows.

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