A student in SLE222 conducted part C of practical 3. They thought they were addi
ID: 144461 • Letter: A
Question
A student in SLE222 conducted part C of practical 3. They thought they were adding in the correct concentration of co-substrates. However, instead of adding in 10 mg/mL (14.6 mM) of NAD+ and 10 mg/mL (14.1 mM) NADH, the student added 0.1 mM NAD+ and 0.1 mM NADH from part A of the practical. They completed the assay and measured the absorbance of their systems. The following data obtained and plotted
i) Describe the trend in the results as depicted in the above graph.
ii) Describe the trend that would have been observed if the correct NAD+ and NADH solutions would have been used and iii) what has gone wrong in the experiment. In your answer describe the reaction catalysed by lacatate dehydrogenase and the change in substrate and products that should have occurred. Include which species is oxidised and reduced, and thus, the form of the co-substrate required for the reaction. (Hint: think about what is being measured in this part of the practical and how the reaction is catalysed by lactate DH)
Part C: Co-substrate requirements of lactate DH 1.0 0.8 5 0.6 0.4 8 3 0.2 0.0 NADH NAD+ NoneExplanation / Answer
i The oxidised form (NAD+) has more absorbance than the reduced form (NADH) the absorbance rate when nothing was added is almost equal to the value obtained when NADH was added.
ii LDH release is mainly governed by oxidised NAD+ so the amount of oxidised energy plus could have been more in order to obtain the result more accurate.
.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.