Effects of a high protein diet and liver disease in an in silico model of human ammonia metabolism

Table 1 Values for reaction velocities scaled to average male liver mass with recommended protein diet

Reaction Velocities	Parameters from the Literature	Organism and Tissue	Parameters Scaled to Liver
V_{NH3 abs} = 0.492 mmol/min^a
V_GLS = (V_{max GLS}[Gln])/(K_{m Gln} + [Gln])	V_{max GLS} = 91.4 nmole/min per mg [25]	Rat Liver	V_{max GLS} = 28.54 mmol/min
V_GLS = (V_{max GLS}[Gln])/(K_{m Gln} + [Gln])	K_{m Gln} = 4.0 mM [26]	Human Recombinant	K_{m Gln} = 4.0 mM
V_{NH3 ex} = 0.004 mmol/min^a
V_CPS1 = (V_{max CPS1}[NH₃])/(K_{m NH3} + [NH₃])	V_{max CPS1} = 45 nmole/min per mg [27]	Human Liver	V_{max CPS1} = 8.05 mmol/min^ab
V_CPS1 = (V_{max CPS1}[NH₃])/(K_{m NH3} + [NH₃])	K_{m NH3} = 0.35 mM [28]	Human Recombinant	K_{m NH3} = 0.35 mM
V_GLUL = (V_{max GLUL}[NH₃])/(K_{m NH3}{1 + ([Gln]/K_{i Gln})} + [NH₃])	V_{max GLUL} = 0.47 μmole/15 min per mg [29]	Rat Liver	V_{max GLUL} = 12.3 mmol/min^b
	K_{m NH3} = 0.15 mM [30]	Human Recombinant	K_{m NH3} = 0.15 mM
	K_{i Gln} = 0.6 mM [31]	Bacillis subtilis	K_{i Gln} = 0.6 mM
V_{Urea ex} = 0.244 mmol/min^a

^aThese values change with protein diet. See methods and discussion for details
^bThese values change with liver condition. See methods and discussion for details

ISSN: 1742-4682