Malate-Aspartate Shuttle

Malate-Aspartate Shuttle

by Andrey K

Life & Natural Systems Biology PSBiology, life sciencesPSBBiochemistry
🎙 Andrey K 👥 852K 📅 June 12, 2015 ⏱ 12 min 👁 202K 📄 tutorial 🧭 2026-08-17
Available in: English (current) Français

Keywords

malate-aspartate shuttleNADHmitochondriaoxaloacetateaspartate

Summary

This educational video by Andrey K explains the malate-aspartate shuttle, a mechanism used by cardiac muscle and liver cells to transport NADH produced during glycolysis from the cytoplasm into the mitochondrial matrix. The shuttle involves a series of enzymatic reactions and antiporter exchanges. In the cytoplasm, NADH reduces oxaloacetate to malate, which is then transported into the matrix in exchange for alpha-ketoglutarate. Inside the matrix, malate is oxidized back to oxaloacetate by mitochondrial malate dehydrogenase, reducing NAD+ to NADH. Oxaloacetate cannot cross the inner membrane, so it is transaminated to aspartate using an amino group from glutamate. Aspartate exits the matrix in exchange for glutamate. In the cytoplasm, aspartate is deaminated to regenerate oxaloacetate and glutamate, completing the cycle. The net effect is the transfer of reducing equivalents from cytoplasmic NADH to mitochondrial NADH. The video then compares ATP yield: the malate-aspartate shuttle delivers electrons to Complex I, resulting in 2.5 ATP per NADH, whereas the glycerol-3-phosphate shuttle delivers to Complex III, yielding 1.5 ATP. The explanation is clear and well-structured, with diagrams, but contains a minor error in the number of protons pumped by Complexes III and IV.

189 words

Critical Evaluation

Value of the Information & Strength of the Argument

The video provides a thorough and systematic explanation of the malate-aspartate shuttle, breaking down each step and emphasizing the purpose of each reaction. The argumentation is logical and builds from the need to transport NADH to the specific molecular mechanisms. The comparison with the glycerol-3-phosphate shuttle and the calculation of ATP yield adds practical value. However, the video does not discuss alternative perspectives or potential controversies, and the minor stoichiometric error slightly undermines the precision of the argument.

Scientific Rigor, Source Quality, Title Accuracy

The video is scientifically accurate overall, but the error in proton pumping stoichiometry (Complex III and IV) is a notable flaw. The content aligns well with standard biochemistry textbooks. The title accurately reflects the content. The description provides links to the lecturer’s website and related resources, but no direct citations to primary literature. The video is a tutorial, so it does not cite external sources, but the explanation is consistent with established knowledge.

166 words

Title / Content Match

Title accurately reflects the content, which focuses exclusively on the malate-aspartate shuttle.

Quality & Reliability

8/10

Clear, accurate explanation of the malate-aspartate shuttle, but minor error in H+ stoichiometry of complexes III and IV.

Key Moments

Markers derived by PSI from the transcript: the creator did not define chapters.

Cited Sources

Concurring Sources

  • Biochemistry Textbook (e.g., Lehninger) — Standard biochemistry textbooks describe the malate-aspartate shuttle similarly.

Dissenting Sources

  • Complex III and IV proton stoichiometry — The video states Complex III pumps 4 H+ and Complex IV pumps 4 H+, but the correct numbers are 4 H+ for Complex III and 2 H+ for Complex IV, as noted by commenters.

Contribution & Novelties

The video provides a clear, step-by-step visual explanation of the malate-aspartate shuttle, which is often a challenging topic for students. It effectively contrasts this shuttle with the glycerol-3-phosphate shuttle, highlighting the difference in ATP yield. The explanation of the antiporter exchanges and transamination reactions is particularly helpful. The video does not introduce new scientific findings but serves as an excellent educational resource.

Pour aller plus loin :

99 words

Radar Profile

The radar profile shows high scores in information quantity, quality, and reliability, with a slightly lower technical level. This indicates a well-balanced educational video that is accessible yet detailed, with minor inaccuracies that slightly reduce the reliability score.

Reliability 8/10

💬 Très positif. Sur les 30 commentaires analysés, la grande majorité exprime une gratitude et une admiration pour la clarté des explications, certains signalant une erreur mineure sur le nombre de protons pompés par les complexes III et IV.