2. The following kinetic data were generated for the enzyme SpB1, there is no bi

Question

2. The following kinetic data were generated for the enzyme SpB1, there is no biologically known function for this enzyme Using the information provided below answer questions 2a 2c All reactions had 0.1 mg/mL SpB1 which based on amino acid sequence and gel filtration column chromatography has a molecular weight of 42,500 Daltons Substrate 1 KM (mM) >50 0.1 0.03 0.9 + 0.5 50 4+1 27+8 Substrate 2 (min lucose lucose lucose alactose alactose alactose 0.01 19+5 6 +2 0.01 0.5+ 0.07 2 0.05 NADP NAD NADP NAD 2a. What is the best substrate or substrates for this enzyme? Explain your conclusion here. (3 points) 2b. If you found that there is a phosphorylated form of the SpB1 protein, called SpB1-P, and this second form has a kea/KM of 7.2 X 107M sec with the substrate or substrates you concluded in part 2a. Which form of SpB1 would be the most efficient enzyme? Explain why and what does this tell us about this enzyme in a biological setting? (4 points) 2c. To the reaction with galactose and NADP you added in 1 mM of glucosamine and observed that the KM for this reaction is now 10+6 mM and the kcat is now 0.7 0.05/min. What type of inhibitor is glucosamine and what is the K for glucosamine? (4 points)

Explanation / Answer

2a) Thebest substrateS are glucose andNADP because 1. According to Michaelis-Menten equation the higher the Kcat is more substrate turned over,so Kcat value is more in the substrates glucose and NADP. 2. Less KM value more velocity of reaction , glukcose and NADP substrates have less values.3.K cat/KM gives measure of enzyme efficiency. 2b)Kcat/KM=. 19*60/.1*10-3=1.14*107/M.sec , even though the Vmax value is somewhat high for SpB1P. here uncompetitive mode of inhibition takes place . 2c)glucosamine is competitive inhibitor as it prevents the enzyme from binding to the substrate.when active site is blocked,the reaction cannot occur.It is like the inhibitor and the substrate are competing for the active site.

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