An enzyme catalyzes a reaction in which the three substrates MgATP, NADPH, and a
ID: 71364 • Letter: A
Question
An enzyme catalyzes a reaction in which the three substrates MgATP, NADPH, and aspartate form the products MgADP, aspartate semi-aldehyde, inorganic phosphate and NADP+, in a series of reactions as below: (steps 1 and 2)
Initial velocity data of the three substrates was collected, and is tabulated below:
Variable Substrate, Changing-Fixed Substrate, Fixed Substrate, Initial Velocity Pattern
MgATP,Aspartate,NADPH ,intersecting
Aspartate,MgATP,NADPH ,intersecting
NADPH,MgATP,Aspartate,parallel
NADPH ,Aspartate,MgATP,parallel
Product Inhibition data was as below:
Product Inhibitor, Variable Substrate, Fixed Substrates,
Product Inhibitor
MgADP, MgATP, Aspartate and NADPH, mixed
MgADP, Aspartate, MgATP and NADPH, mixed
MgADP, NADPH, MgATP and Aspartate, Competitive
NADP+ MgATP, Aspartate and NADPH, Uncompetitive
NADP+ , Aspartate, MgATP and NADPH, Uncompetitive
NADP+ , NADPH, MgATP and Aspartate,Mixed
inorganic phosphate, MgATP, Aspartate and NADPH, Uncompetitive
inorganic phosphate, Aspartate, MgATP and NADPH, Uncompetitive
inorganic phosphate, NADPH, MgATP and Aspartate, Uncompetitive
aspartate semi-aldehyde, MgATP, Aspartate and NADPH, Competitive
aspartate semi-aldehyde, Aspartate, MgATP and NADPH,Mixed
aspartate semi-aldehyde, NADPH, MgATP and Aspartate, Uncompetitive
Explanation / Answer
The enzyme aspartate-semialdehyde dehydrogenase (ASADH) belongs to the family oxidoreductases, and it is involved in the conversion of amino acid aspartate to aspartate-semialdehyde. It an important enzyme present in both eukaryotes, like higher plants and prokaryotes, like bacteria. The reaction catalyzed by the ASADH is as follows:
L-4-aspartyl phosphate + NADPH + H+ L-aspartate 4-semialdehyde + phosphate + NADP+
The Initial velocity data:
Thus, the correct option is (3).
The Product Inhibition data:
Thus, the correct option is (10).