Pyruvate + $NAD^+$ + CoASH $\longrightarrow$ Acetyl-S-CoA + NADH + $CO_2$
This oxidation reaction occurs in mitochondria and is carried out in presence of the enzyme
Enzyme Catalyzing Pyruvate Oxidation
The conversion of pyruvate to acetyl-CoA is a critical step in cellular respiration, bridging glycolysis and the citric acid cycle. This process takes place within the mitochondria.
Pyruvate Oxidation Reaction Details
This reaction is an oxidative decarboxylation. Pyruvate is oxidized, releasing carbon dioxide ($CO_2$), and forming acetyl-CoA. $NAD^+$ is reduced to NADH during this process. The simplified equation is:
$ \text{Pyruvate} + NAD^+ + \text{CoASH} \longrightarrow \text{Acetyl-S-CoA} + \text{NADH} + CO_2 $
Mitochondrial Enzyme Identification
The enzyme complex responsible for catalyzing this specific irreversible reaction in the mitochondrial matrix is:
- Pyruvate dehydrogenase complex. This enzyme converts pyruvate into acetyl-CoA, which then enters the citric acid cycle.
Enzyme Role Clarification
The other options represent enzymes with different metabolic functions:
- Pyruvate kinase: Acts in the final step of glycolysis, converting phosphoenolpyruvate to pyruvate.
- Pyruvate decarboxylase: Primarily found in yeast and bacteria, it removes a carboxyl group from pyruvate, yielding acetaldehyde and $CO_2$.
- Pyruvate carboxylase: Catalyzes the synthesis of oxaloacetate from pyruvate, a key step in gluconeogenesis and anaplerosis.
Important Questions from Plant Biochemistry Enzymes Reactions
- Match the following digestive enzymes in Column I with their respective functions in Column II.
Column I Column II P. Erepsin (i) converts proteins to peptides Q. Steapsin (ii) activates trypsinogen to trypsin R. Pepsin (iii) converts fat into fatty acid and glycerol S. Enterokinase (iv) converts polypeptides to amino acids - Match the proteins in Column I with the organs in which they are maximally expressed in Column II.
Column I Column II P. Keratin (i) Liver Q. Surfactants (ii) Pancreas R. Pro-carboxypeptidase (iii) Lung S. Albumin (iv) Skin Identify the free radicals (marked as '?') in sequence from the inter-conversion of reactive oxygen species as shown below.
$O_2\rightarrow? \rightarrow H_2O_2 \rightarrow? \rightarrow H_2O$
P. $\mathrm{O}_2^{\bullet -}$
Q. $OH^-$
R. $HO_2^{-}$
S. $\ {}^{1}\mathrm{O}_2$
- Choose the CORRECT set of matches between group I and group II in relation to nitrogen fixation and assimilation
GROUP I GROUP II P. Nitrobacter 1. $NO_3^-$ $\rightarrow$ $NO_2^-$ Q. Nitrite reductase 2. $N_2$ $\rightarrow$ $2NH_3$ R. Nitrogenase 3. $NO_2^-$ $\rightarrow$ $NH_4^+$ S. Nitrate reductase 4. $NO_2^-$ $\rightarrow$ $NO_3^-$ - Select the CORRECT combination by matching Group-I with Group-II.
Group-I Group-II P. Photorespiration 1. Glutamate $\rightarrow$ 2-Oxglutarate Q. Respiration 2. Acetyl-CoA $\rightarrow$ Malonyl-CoA R. Amino acid degradation 3. 2-Oxglutarate $\rightarrow$ Succinyl-CoA S. Fatty acid synthesis 4. Glycine $\rightarrow$ Serine
